Omega Thermocouple (in IHS) Vs. Onboard Sensors

Accidently posted this in wampeters...

Please Read the following.. You will now understand why I so emphatically state that the onboard sensors are totaly useless.



Test System
DFI nF4 Ulta-D w/ Vcore, Vdimm and Vtt mod
AMD A64 3000+ Winchester with T-type thermocouple mod to IHS (lapped IHS)
2x512mb OCZ PC4800 EL plat
ATI X800GTO
Omega HH506RA Multilogger Thermometer w/2 T-type thermocouples

Cooling System
Cooltechnica MP-05 SP Pro
Danger Den Maze4 GPU
Cooltechnica AquaExtreme 50Z 12VDC Pump
Danger Den Black Ice Extreme 2
2x Yate Loon 120mm fans @12v
Daul 5inch Bay Res
Clearflex 60 1/2" ID 3/4"OD tubing
Loop Order - Pump -> GPU -> CPU -> Radiator -> Reservoir


Test Method
Ambient temp taken with 36gague T-type thermocouple mounted in front of intake fan of radiator
Actual CPU temp taken with 36gauge T-type thermocouple embedded in CPU IHS with Omega bond OB-101 thermal epoxy
CPU Load created with S&M v1.7.6 beta with FPU test
Temperatures were allowed to settle for approximately 30 minutes before readings were taken.




Thermocouple

Ambient
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23.2 +-0.1C

Idle
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27.7C (with 22.7 ambient)

Load
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32.2C

dT (CPU Load to Ambient)
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9.0C



Onboard Sensor

Idle
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27-29C (ambient between 22.7-23.2)

Load
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40 +-1C (jumps around)

Ha, 8C diff.

yup.. just goes to show you how useless they are.

Unless, of course, the onboard sensor was actually inside the CPU core.

Thanks for the infor. MaxxxRacer.

So the actual Load temp's much lower than the mobo report.

indeed it is much lower..

From idle Ive noticed about a 4-5C jump in temps when loading the cpu.. this is independent of ambient temp.. Not the 12C jump that the onboard sensors show.

Overconfidence: the onboard amd sensor is IN the cpu... if you setup a proper calibration curve and use a Maxim thermistor sensor + SM bus reader, you can actually get accurate results from the onboard sensor... but its a pain in the arse and requires modding your mobo and cpu.

Quote:

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Originally Posted by MaxxxRacer

Overconfidence: the onboard amd sensor is IN the cpu... if you setup a proper calibration curve and use a Maxim thermistor sensor + SM bus reader, you can actually get accurate results from the onboard sensor... but its a pain in the arse and requires modding your mobo and cpu.

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But.. technically... the temperatures would be slightly higher on the inner sensor, wouldn't they? (Not the 8C that it's suggesting right now, but something?)

well I will admit that the IHS temp is a bit insulated from the core, but the IHS temp provides an average temp of the cpu... About 70% (guestimate here) of the cpus heat goes directly upwards, so where the probe is, most of the energy will be transfered, thus providing a good analysis of the heat being outputted..

anyway back to what you asked. the core temp will be a litttle higher (in some spots on the core) than the temp reported by the IHS.. but here is the thing.. the onboard sensor is placed on the edge of the core where it is the coolest... I even asked an AMD engineer about this and this was the info he provided.. he also poitned out that in this section of the CPU (on A64 anyway) the temp is a bit lower than the rest of the core...

So if the temp where the sensor is is lower than the rest of the core and the sensor is reporting 8C above what I am reading with the IHS temp... well u can see where this is going.

MaxxxRacer, is this appiled to IHS less cpu as well ?

i'm asking because of i'm running opty170, IHS off, my load temp, according to MBM5 is about 4-5 C higher than idle temp. (idle ~ 28-29C, load ~ 32-33C ).

the temp difference between load and idle? No idea what an IHS less cpu will do compared to an IHS capped cpu.. with the method of temperature measurement that I am using it is impossible to mount the sensor to an IHS' less cpu..

BUT your idle and load temps do look alot more realistic than most... Although i should point out that the 3.5-5C delta I demonstrated was with a 2.25ghz 1.573v winchester will not be the same as your opteron 170 which puts out alot more heat especailly if its overclocked.. (although the output could be less than i am assuming if your running like 1.2v or something rediculous like that.

I'd like to see this on a DFI Expert. My Smartguardian on my latest Expert which is an older revision reports temps below ambient during idle.

Nice job maxxx :fact:
Thanks for the info, I just stressed to view the temperature of my processor was fluctuating. :nono:

OMG ! Now I understand how much the onboard sensors suck.

Quote:

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Originally Posted by Coroner Kyle

I'd like to see this on a DFI Expert. My Smartguardian on my latest Expert which is an older revision reports temps below ambient during idle.

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so send me an expert ;)

While I understand that on-board temperature sensors (OBTS) suck, it yould really be nice if they scaled linearly. It appears as thought the OBTS is off by a percentage of the actual temp, making it difficult and almost useless to setup an offset which some temp monitoring programs allow you do.

You can't even compare your own before and after temps with any modicum of reliability..... what a bummer.

One thing I did notice though.. the idle temp of the cpu follows the actual temp relativley closely, even with changing ambients. my ambient gets to around 12C at night if i leave the window open.. when its cool in my room the cpu will idle in the low to mid 20's.. the onboard sensor reflects this as well, and my load temps are a bit lower as well. BUT with the lower the ambient temp, the worse the accuracy of the load temp.. for instance when i ran S&M when it was about 14-15C ambient, the differential between actual cpu temp and ITE was about 10.0C... earlier today when ambient was 22.4 the difference between actual and ITE was lower...

Hi Maxxx :) . Make such statement as "just goes to show you how useless they are." is absolutly unadapted. It isn't worth to make such tests if you start arguing with that kind of statement without knowning what you do, what you measure and what is the influence of whole parts below your thermocouple. You are testing with pre-fabricated ideas about sensors capabilities (like a lot of people) and this is not correct ! Yes, temperatures reported by sensors (and more exactly by the chip) can have an offset due to traces on PCB, noise, etc., but generally, evolution is fine (diode inside die is good and known with a certain tolerance, remember yourself the Phaestus calibration of 1700+, it was linear).

Thermocouple T° and die T° give 2 interesting informations. Obviously, the die is hotter than thermocouple because we need to take in account thermal resistances of the IHS (quasi negligible here), of TIM1 (~0.04-0.07°C/W) and of the silicon die (often based on 0.03-0.04°C/W). The sum of these thermal resistances isn't small at all, mainly on AMD with their poor TIM1. There's nothing strange to get an 8°C difference between thermocouple and cpu here, on the contrary, it's realistic and your die T° is quite good in regards of dissipated power. Please, stop thinking that a die don't warm, it's false (hot spots, etc.)... You have no idea of what a TIM (and others parts) influences thermal gradient. One proof (need more controlled data and studies cases but it's a beginning) is that at very low power at Idle, thermocouple T° and die T° are in the same range and close, because T° gradient occasionned by previous thermal resistances is small (low power->low gradient). The better will be at 0 power to see the real offset, but we need to use external circuitry to control internal diode, not easy. When power raises, this gradient raises too linerarly (pay attention to secondary losses) : the more power generated, the more gradient is and the more the difference between thermcouple and die will be. You need to control environnement around mobo, a big change in ambiant will change influence of secondary losses (draught?thermal paste settled? other parameter?), it's not necessary linear and it's probably not... Need a lot of testing to understand thermal mechanisms and influences here to define an acceptable way of testing.

Roscal

I agree with rosco here. The information provided thus far is fairly meaningless, sorry Maxxx. I know it is just a start (hopefully) but it is going to take lots and lots of data and tests and of critical importance is the control of ambient temps. What I will say, is that this is the sort of temp measurement I prefer, seeing the die temp and the IHS temp instead of just one or the other. Anyway, hopefully this is just a start and hey, you got Roscal to register :)

rosco.. interesting info.. and not to sound like an arse.. all of which i know (probably from reading your posts are procooling).


guys, maybe you didnt hear, but the ambient temps during the load testing didnt vary but by .1C. If you guys think it would be beneficial I could add another thermocouple infront of the radiator fans?

"The information provided thus far is fairly meaningless"

how is it meaningless, and how would you go about making it more meaningfull.

I suppose the thread should have been entitled "Omega thermocouple vs. Motherboard" because, as rosco pointed out, the on die sensor, when attached to a proper reading source, is surprisingly linear.

One other thing I forgot to mention in the test setup. I am using artic lumiere which, according to the arctic silver guys, settles in all of 15-30 minutes.

In any case, I appreciate the criticisms (despite however defensive I may get), and would greatly appreciate any ideas you guys might have on how to improve on the test methods.


On a side note: I was just thinking to myself about the calibration methods derek used on the 1700 and A64 chip... they were done with no power going through the chip... what happens when you put power through the chip? does the calibration still hold true, or is it effected by the various signals in te chip?

I ask this question not to attack Derek or his methods (infact I tried the same method and learn a good portion of what I know about testing directly from him), but rather as an honest question.

If the on die snesor is effected by the chip running or not running, that does indeed pose an interesting challenge. and on the same note.. Is the thermocouuple I have embeded in the IHS affected by the chip running too? and if so, how would we ever go about overcoming such obstacles?

Could you not cut a slot into the heatsink and mount a temp sensor in this ? That way you could run without the IHS, and if you mount the sensor correctly you will get the temp at the surface of the die.

Just my 2 cents.

Maxxx, I should have stated that the results thus far are kind of meaningless. I think it is common sense (?) that the die temp would be higher than the IHS temp. The data that will be interesting to me, is the IHS to die temp difference among different water blocks. I still think these 2 will not scale in a linear fashion. Bill keeps saying that die temps are meaningless and tcase is where it is at. How could having both sets of data hurt?

Maxx > Sorry, I read again the entire topic and I have to complete my answer above, because I forgot something and I was misleading myself (reading too fast probably). I thought you used water T° to get the deltaT, but you used only ambiant air sucked at radiator. This induces some variation generally, and mostly you have a GPU WB in the loop -> you mix all of them and you get an unbelievable disorder in your data at final...

What do you want to catch exactly? Whole system perf or only WB perf? Because it's not the same. I read others threads and I saw you want to get WB performances principally, it's OK, but do we need a GPU in the loop to do that? No (and if it's only a first try, no abusive conclusions should be taken as above). The loop should contain the minimum to avoid undesired variance (you don't control GPU dissipated power for example). Here, you are introducing some factors which are not necessary to establish the CPU WB behaviour (without forget flow for future data). You should take the water T° just at inlet of the WB, it's more precise and consistent (physicals parameters need to be as close as possible of the things you want to measure, always). T° in front of a radiator can vary a bit because of fan recirculation at edges and hub dead zone, so multiples thermocouples are generally recommended in each quadrant, but here we don't need them, water T° is far easier to get. You'll have a waterchiller I believe, but it's not really necessary too. It's a facility to get faster results because we don't have to wait a long equilibrium establishement with radiator. But if you decide to keep you water, let's say @30°C +/- 1°C (not important to get 30.00°C, you won't see any difference at 31°C in your C/W curves because water properties don't change radically within 1-2°C), you can play with fan regulation slowly to keep water in your range, it's not difficult when air T° is quasi constant because you can adjust precisely the fan before reaching equilibrium (a first try give some infos about final T°). I do that, just a habit.

About diode calibration, I think there's no interaction with others CPU parts because it's just a simple diode packed into the die to measure current response through it. The first idea in my mind is to verify it (or at least have an idea) with a massive underclock to get low dissipated power at Idle, if it's OK (no interactions with power going though the chip or mobo connexions), you'll find again a water T° really close of your die T° (low power > low gradient > low T° difference). Good luck for your tests.

PS: Is your first sentence ("[..]like an arse[..]") a criticism ? I don't understand well the meaning...

XS forum is ultraaaaaa slow at this time, isn't it?

rosco, this was merely a brief snipet to show the oddities of the onboard sensor..

for any testing that will be for reviews i will follow a much more error hardned method of testing... Chiller instead of radiator, waterblock inlet and outlet temps (water temps recorded with T type thermocouples), with the inlet temp held constant with the haake chiller.. ambient temp also recorded and the cpu will be on a dedciated loop powered by an iwaki WMD20RLT.

niksub1: it is common sense that the die temp will be higher than the IHS temp, but the amount is a bit much i think, and the variation between die and ihs temp with varying ambient temps.. for any testing, the sensor in the IHS is fine, even if it may not be exactly with the core temp, becuase it will be a comparison between different waterblocks with the same testing methods... (I hope that made sense). But just for you I will include the core temps for all data points, however useles I think it is. lol.

Tcase IIRC is the ihs temp where i am measuring (been a few weeks since i looked at an intel tech doc with the names of the measurements points). If so, then I would have to disgree with bill.. the actual core temp is what we REALLy want to know... while Tcase is very useful and perfectly fine for the kind of testing i will be doing, if you want the absolute best conception of how exactly something is cooling the cpu, the core temp is where its at. but with that said, the on die sensor is poorly placed for such operations..


the like an arse comment was not a criticism aimed at you. I was merely pointing out that what i was about to say may come off as rude, or snide, and it was not my intention.

while I dont have a calibrated way of measuring the temperature of the die (sold my maxim kit to fund my current goings on), i will undervolt and under:banana::banana::banana::banana: the cpu to its lowest levels tonight and re-run the tests.. If i have time i will also remove the gpu from the loop.

Quote:

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Originally Posted by MaxxxRacer

niksub1: it is common sense that the die temp will be higher than the IHS temp, but the amount is a bit much i think, and the variation between die and ihs temp with varying ambient temps.. for any testing, the sensor in the IHS is fine, even if it may not be exactly with the core temp, becuase it will be a comparison between different waterblocks with the same testing methods... (I hope that made sense). But just for you I will include the core temps for all data points, however useles I think it is. lol.

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Oh but it is not useless. This was my whole argument against TTV testing... all that is shown and known is Tcase. I am interested in how the 2 scale together (if at all) with respect to different blocks. Will there ALWAYS be an 8C difference between core and IHS? Will that gap widen or shorten depending on the block? All very interesting and not useless at all.

^^
Maxx has already noted a difference of 2c delta when ambient is lower. I am very much interested in die versus tcase temps also...

nik, showing the difference between Tcase and Tdie is not uselss, but rather the data provided from ITE is rather useless as the accuracy of it is dubious at best.

with the maxim kit hooked up to the cpu after calibration, showing both Tcase and Tdie would be VERY interesting..

Plywood99, i showed that the delta is not consitent with different ambients.. nik was wondering aobut consistency between different waterblocks.

Quote:

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Originally Posted by nikhsub1

How could having both sets of data hurt?

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how will they help? they will not in any form invalidate or validate one method or another, they will do nothing but raise questions (mostly old) that cannot be answered by anyone here. please step back and look at what maxxx is trying to do here: reliably measure the temperature as relates to thermal tranfer. and I still don't get how the DIE TEMP you are incessantly preaching about will get him closer to his goal.

I will also be calculating heat output by measuring the dT between waterblock in and waterlbock out temperatures... along with flow this will give wattages... with only .1C resoution im not sure how useful it will be, but it will give an approximation.

Quote:

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Originally Posted by snowwie

please step back and look at what maxxx is trying to do here: reliably measure the temperature as relates to thermal tranfer. and I still don't get how the DIE TEMP you are incessantly preaching about will get him closer to his goal.

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Only measuring Tcase IMO is not reliable. I you don't get how the die temp relates to anything, put your head back in the sand.

okay, i see we all have opinions...

you say Tcase is not reliable
maxxx says Tdiode is not reliable

i'm glad we've made so much progress (maxxx what are you getting yourself into?!)

snowwie, I ask myself that on a regular basis..

to make everyone happy, the best way is to measure Tdiode with the maxim kit as well as Tcase with the embedded thermocouple (although an RTD probe attached to a high end fluke or omega .01C resolution thermometer would be better)... but I refuse to muck with this CPU more than it already is for fear of breaking it.

There is no doubt that every motherboards reading of the on die sensor is questionable from board to board. But 8C here doesn't seem all that crazy to me though based on silicon and AMD TIM thermal resitivity. The only good way to show this effect is to hold the same IHS probe temp constant and record say 10 different boards on die reading. Then we could actually say the "motherboard sensors" are very inaccurate.

My thoughts on this "on die" vs "probe temp" data... If we look at it from the perspective of testing water blocks only then the on die temp doesn't really matter because testing on the IHS is sufficent. However for completeness there is no reason not take the on die temp reading as it has side interest for learning other things besides how a water block performs(i.e. a better understanding of IHS temp vs on die temp.

Quote:

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On a side note: I was just thinking to myself about the calibration methods derek used on the 1700 and A64 chip... they were done with no power going through the chip... what happens when you put power through the chip? does the calibration still hold true, or is it effected by the various signals in te chip?

I ask this question not to attack Derek or his methods (infact I tried the same method and learn a good portion of what I know about testing directly from him), but rather as an honest question.

If the on die snesor is effected by the chip running or not running, that does indeed pose an interesting challenge. and on the same note.. Is the thermocouuple I have embeded in the IHS affected by the chip running too? and if so, how would we ever go about overcoming such obstacles?

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Well we can safely say if you are generating any heat(power applied) in the core and calibrating to an extrenal source then all bets are off, and why the calibration should be done with no power. Does signals or EMI have an effect? Now that's a good question. I'll say if you are always running the chip and the same freq and voltage you could say that any signal interference would at least induce the same .1C (or whatever it might be) shift. If you are just testing water blocks I don't think it would matter because each block is getting the same shift.

Quote:

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Will there ALWAYS be an 8C difference between core and IHS? Will that gap widen or shorten depending on the block? All very interesting and not useless at all.

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Of course the 8C will change. All factors held constant it depends on CPU heat load. I think we have already seen a glimpse of this by Maxxx's claim of a small delta at idle, exactly what I would think would happen. If we start changing factors, in this case the water block, then we will probably see a difference in the delta from the best to worst block. I agree with you as I said above that the data should be taken, but it would be for a different study then the study of water block performance. You only need one data point on the "other side" of the water block to determine performance.

If you could put 1,000 probes from the center of the die out to the center of the water the temperature at each probe would look something like this with temp on vertical and distance from core on the horizontal(except at turbulent flow it isn't linear but I'm too tired to draw it right also assumes constant water temp). This isn't to scale or anything, but the point is the steeper slope at load, then at idle, and at off

http://home.comcast.net/~aicjofs/heat.png

"My thoughts on this "on die" vs "probe temp" data... If we look at it from the perspective of testing water blocks only then the on die temp doesn't really matter because testing on the IHS is sufficent. However for completeness there is no reason not take the on die temp reading as it has side interest for learning other things besides how a water block performs(i.e. a better understanding of IHS temp vs on die temp."

I am very interested in these temperatures. For instance I and many others are convinced that the tim1 layer on AMD cpu's "degrades" over repeated mountings. Recording core and ihs temps over many many mountings will prove or disprove this.

I just can't trust this experiment since the type of sensor is not the only variable.

I can easily believe that two regions of the die at one time could hold temperature difference of 8C or more. MOst people imagine the core to be one uniform temp, but it is not. 0-dimensional data describing a 3-dimensional subject.

*sigh* i'm getting sick of this discussion. will it make that big of a difference in the final results? i doubt it. theres always going to be the minutiae and so on and so forth... deal with it. I still dont understand why people have been moving away from heat dies and on to actual processors. fully loading a processor properly consistently would be a lot harder than just flipping a switch in my opinion. The whole testing methodology debate/debacle is quickly spiraling out of control.

i wouldnt call this completely accurate, your measuring OUTSIDE of the core, and through a piece of metal which is dissipating heat ALL around the IHS. your sensor isnt getting the full concentration of the heat.

and its no where close to being inside the core.

aicjofs: I like that graph.. what software did you make it in? Im looking for good graph making software. (for reviews)

Quote:

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Originally Posted by WeStSiDePLaYa

i wouldnt call this completely accurate, your measuring OUTSIDE of the core, and through a piece of metal which is dissipating heat ALL around the IHS. your sensor isnt getting the full concentration of the heat.

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I make no claim of being completely accurate. If I were to make such a claim, all of you would be justified in slapping me with a 20lb trout.

While the IHS is disipating heat ALL around itself, you need to take not that MOST of the heat is being disipated directly above the core and not near the extremities.. and infact, the more effeciently you cool the core, the less heat gets transfered towards the edges of the IHS.. this has been documented by Joe at overclockers.

Quote:

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Originally Posted by MaxxxRacer

While the IHS is disipating heat ALL around itself, you need to take not that MOST of the heat is being disipated directly above the core and not near the extremities

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I disagree. If you look at robotech's test results you'll see that the edge of the heat spreader is ~4.5C above the water temp. When you take into consideration that the ihs is in contact with a efficient waterblock and more than 9 times the size of the core, this 4.5C has to be considered huge. Such temps for such a large area can only be reached if alot of heat is passing through it.

In case of a block like the apogee, I would wager that as much as 80% of the total heat load is being transfered outside the primeter of the core

The next question is why is so much heat being spread through a relativly thin IHS. "My theory" is that it has to do with the high resistance (compared to the copper spreader) of the tim joint. As thin as the spreader is it's much easier for the heat to move lateraly than to move straight through the TIM joint. The more the heat spreads, the lower the TIM resistance becomes (due to the now larger heat transfer area).

Block design also plays a role and I think a block like the apogee compliments the above effects.

Quote:

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Originally Posted by FLB

In case of a block like the apogee, I would wager that as much as 80% of the total heat load is being transfered outside the primeter of the core

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That defys all known ideas of thermodynamics. If you look at a thermal image of the heat transfer you will see most of it going straight up. A bad TIM1 joint will not make the heat go everywhere but up.. The heat still has to enter the IHS through the TIM1 joint.

I think I will have to thermal epoxy another probe to the side of the IHS to show some more data, and show the delta between IHS center and IHS edge for different waterblocks.. Now only if only I had a 10 input thermometer.

Quote:

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Originally Posted by MaxxxRacer

That defys all known ideas of thermodynamics.

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All the better! For too long people have thought that the IHS had minimal effect. I've given it a lot of thought myself and the above conclusion is the only one that can explain the high edge temp that robotech observed. I'm looking forward to your results

Well to be fank a 5C delta between water and IHS edge is pretty small. It is by NO means insignificant, but compared to the delta between core temp and water, there is a much larger difference.

Quote:

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Originally Posted by MaxxxRacer

Well to be fank a 5C delta between water and IHS edge is pretty small. It is by NO means insignificant, but compared to the delta between core temp and water, there is a much larger difference.

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You need to take the size into proper account. For instance, at half the temp of the IHS center, the 9x larger outer perimeter will still be transfering ~4.5 times the heat load of the core area. This is assuming that the transfer efficiency of the block is the same throughout the contact area, which of course it isn't.

So the next question is how much does it differ. I don't expect a block like the apogee to differ much (my guess, 20% tops)

Question regarding your test setup: What speed and volts is the core running at? Does the water temp and IHS temp report the same thing when the computer is off (pump still running of course)? I'm only asking this because the 5C temp at idle seems a little high to me.

I will most likely be running at 2.3ghz with 1.600V going through it. Rather high voltage, but the higher heat output helps with measurements. bigger deltas are alot easier to measure.

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This is assuming that the transfer efficiency of the block is the same throughout the contact area, which of course it isn't.

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well that makes your entire point (that paragraph) rather pointless..

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Originally Posted by MaxxxRacer

well that makes your entire point (that paragraph) rather pointless..

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Hardly. Even if we make an assumption that the heat transfer efficiency is twice as good over the core as it is over the rest of the surface, we still end up with 2.25x more heat being transfered outside the core.

So with half the surface temp and half the block efficiency, ~70% of the heat load will still be transfered outside the core area and there is no way that a block like the apogee will differ that much.

Quote:

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Originally Posted by FLB

I disagree. If you look at robotech's test results you'll see that the edge of the heat spreader is ~4.5C above the water temp. When you take into consideration that the ihs is in contact with a efficient waterblock and more than 9 times the size of the core, this 4.5C has to be considered huge. Such temps for such a large area can only be reached if alot of heat is passing through it.

In case of a block like the apogee, I would wager that as much as 80% of the total heat load is being transfered outside the primeter of the core

The next question is why is so much heat being spread through a relativly thin IHS. "My theory" is that it has to do with the high resistance (compared to the copper spreader) of the tim joint. As thin as the spreader is it's much easier for the heat to move lateraly than to move straight through the TIM joint. The more the heat spreads, the lower the TIM resistance becomes (due to the now larger heat transfer area).

Block design also plays a role and I think a block like the apogee compliments the above effects.

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FLB, you are forgetting a couple things here.

1) Maxx is correct when he said most of the heat is transfered directly above the core. But there are other things at work here. The ihs is also covering the whole chip. So heat from the sides of the core and from the surrounding silicon will be transferd to the ihs through the surrounding air and the ihs edge contacting the chip itself. This is what is causing the majority of the temperature difference.

2) Your thoughts on tim1 are totally incorrect. Since tim1 is the only thing connecting the core to the ihs, almost all the heat must pass through tim1. There is no lateral spreading happening the way you mentioned it. Remember tim1 covers the core and there for is basically the same size as the core.

Quote:

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Originally Posted by Plywood99

2) Your thoughts on tim1 are totally incorrect. Since tim1 is the only thing connecting the core to the ihs, almost all the heat must pass through tim1. There is no lateral spreading happening the way you mentioned it. Remember tim1 covers the core and there for is basically the same size as the core.

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I wasn't talking about TIM1. I was talking about TIM2.

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Originally Posted by FLB

I wasn't talking about TIM1. I was talking about TIM2.

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Lol, so you were. My brain is on autopilot sometimes.

Yes resistance of tim2 does have an effect on heat transfer as you stated. Another reason I hate ihs's. They confuse the issue too much...

I don't have a lot of time to reply but

Maxxx I just used Paint Shop Pro because I thought it would be easier then making up numbers to satisfy what I wanted to say. Honestly I usually just use Excel which is rather limited.

As for what FLB is saying, I'd like to read Robotech's testing when I get a chance. Is it in this forum if I search or another forum. Sounds interesting. If measuring the side of the IHS, what was done to ensure that any warmer ambient air, if any, from power mosfets etc wasn't sqewing the reading?

I wish I had more time but I'll state a concern I have. How are we referencing TIM1? Seems as a side study people are concerned about the degrading nature of TIM1 joint. In fact a Intel CPU with the solder TIM would reduce variation a bit for this test. Surely Maxxx reseating the blocks 50 times is going to pump some "paste" out of that interface. Normally I'd say a few mountings would have a negligible effect(at least for the resolution this test is capable of measuring, or as much as CPU to CPU variation) as TIM2 junction would be far less repeatable and have a larger impact, but for the number of times we are reseating there needs to be some sort of baseline before and after testing to ensure it has a negligible effect on the results. Would a CPU at lowest multi, lowest HTT, and .9v be too much to fry a CPU without a heatsink/block? Have to consult white papers I guess. If you could reach steady state without frying the CPU at a known ambinet then you could see if TIM1 degraded over the numerous mountings and effected some of the blocks data.

I also wonder if the resolution ability of this test will allow us to say block 1 is better then block 2 which is better then block 7, or if due to accuracy concerns we will only be able to say blocks 1,4, and 5 are better then 2,3,and 8, which are better then 6,7,9 and 10.

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Originally Posted by FLB

The next question is why is so much heat being spread through a relativly thin IHS. "My theory" is that it has to do with the high resistance (compared to the copper spreader) of the tim joint. As thin as the spreader is it's much easier for the heat to move lateraly than to move straight through the TIM joint. The more the heat spreads, the lower the TIM resistance becomes (due to the now larger heat transfer area).

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The problem with your theory is that not so much of the heat is being spread through the IHS as you think...

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Originally Posted by aicjofs

As for what FLB is saying, I'd like to read Robotech's testing when I get a chance. Is it in this forum if I search or another forum. Sounds interesting. If measuring the side of the IHS, what was done to ensure that any warmer ambient air, if any, from power mosfets etc wasn't sqewing the reading?

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Here's the link to the review

http://www.systemcooling.com/swiftech_apogee-01.html

robotech is a fairly smart guy so I assume he took proper precautions but it still would be nice to see a measurement from another source. Hopefully Maxx will be able to get a reading in the near future plus he will have a center IHS temp to compare it to which robotech didn't have.

Here I am getting all wrapped up in this. *sigh* Better then watching American Idol with the woman though.

To stop the side distractions a very clear goal and testing method needs to be established. So far it seems to be evolving which is fine. What info are we after? Are we measuring pure waterblock performance or leaving that job to the block makers? Is it more encompassing then Maxxx has the tools for at the current time? Would forum users get more out of what the "average Joe" will see temp wise at the IHS if the "average Joe" followed the directions for mounting and applying thermal compound from the vendor and had the same pump and radiator as tested. Or are we after something else.

What I am about to say is all hypothetical. Lets say in a lab enviroment the Storm outperforms a TDX for raw heat transfer performance, but what if 9 out of 10 users have an easier time mounting the TDX to lab specs, where only 5 out of 10 can mount the Storm properly to get those ideal temps. What block is then best? What exactly are we interested in?

So are we studying absolute heat transfer performance of the blocks or block performance as veiwed from the "average Joe", or some other study. If we define what we are looking for then some of this side talk can be more clearly focused. I don't really care what is decided as the goal, I would be interested in either of my exampes or something else, we just need a clearly defined one so all this excess energy eveyone has is properly channeled.

edit: thanks for the link FLB.

aicjofs: I am after the quantitaver performance of the waterblocks over a range of flowrates.

Mounting will be standardized to weed out issues there, but I will "review" the block in its entirety. So if a waterblock has horrible mounting issues, and is near impossible to get a good mount with the stock gear, I wil state as such.

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s it more encompassing then Maxxx has the tools for at the current time?

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Yes and No. I can do the tests, but for the ultimate in accuracy and error elimination, I would need higher end equipment and an envirochamber, plus a brand new spiffy RTD based Chiller. Is my current equipment capable of doing the task at hand, and doing so with acceptable accuracy. Most certainly.

What do we deem "acceptable"? I would say, getting the general performance trends of each waterblock, with respect to flow and pressure, and getting each perofrmance curve ranked correctly.