Quad Core Phasing and Information : Read it here!

[n00b 0f l337]

I hope to use this thread as a compilation of sorts for peoples temperatures with certain unit combinations, but also to remove excess posts regarding Vapochill and Nventiv units on quad cores.

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Major thing here is that stock Vapochills and Nventiv units are not up to quad core heat load. Many people see quick depreciation in temperatures after about two weeks, but more in vapochills then mach's. I propose this is due to liquid floodback wearing at the compressor and depleted efficiency.

Bottom line is, these stock manufactured units and even some modded ones are unable to cope with what we guess at between 250 and 275 watts of load.

Either much shorter capillary tubing, and/or a switch to a larger ID capillary is what we may need to start considering. As 5-6 feet of .031 is not appealing, I'm making the move to .036 for these high heat loads and using around 11 feet. This will let me subcool effectively as well.

Lets build up the ideas guys.

[Drag]

it would still be better cooling then air ore water

[n00b 0f l337]

Not so much, killing the compressor due to liquid slogging would be majorly costly.

[{.bLanK} GoD]

If the heat load was too much, wouldn't the compressor die from overheating due to the lack of suction cooling?

[n00b 0f l337]

Possibly both! Thats a very valid point but then a compressor cooling refrigerant, like r11, could be the solution.

[{.bLanK} GoD]

I'm still not sold on the flood back theorem. If you heat load is greater than the unit is tuned for, then you do not have enough refrigerant feed to the evaporator. Solution is more refrigerant, i.e shorter cap tube. Too much refrigerant will cause flood back, not too little.

[n00b 0f l337]

Right theres a ton of variables adding into this. But also with our evaps you can only have so much expansion without pressures rising. More expansion from more pressure creates higher low side pressures and higher temps, then temps rise. Of course we need to get more refrigerant in, but its not all about shortening the cap tube, resizing to a larger ID will help.

But why then would overtime the unit become non-functional. I think either the evap is flooding out of control, or the compressors over heating. Possibly both as possibly the liquid that does get to the compressor doesnt cool it but only gets into the compression process and harms it.

Overall its time to work on solutions:
1) Larger compressors and condensers to help with lower temperatures.
2) Not shorter captubes, but longer larger ID captubes to deliver enough refrigerant but with still subcooling of the capillary.
3) Proper compressor cooling provided by 1 and 2.

[{.bLanK} GoD]

Liquid flooding back to the compressor has an unmistakable sound. Sounds a bit like a deep fryer cooking chips I haven't heard of anybody saying their LS is cooking chips yet.
As for performance dropping over time, I'm not sure, I reckon if the evap was flooding out of control it would happen pretty much as soon as the excessive heat load was attached. Maybe with a very excessive heat load for a unit tuned for something much less, the compressor is on a very steep downhill fight to an ugly and painful death? lol

[n00b 0f l337]

I think you got some awesome idea's as to why Blank. But i have heard Vapo's under the load tester sounding like a deep fryer, PC Ice units too. Mach's accumulator actally works though.

With the evap flooding cooling still occurs though and so does the compressor damage, then the cooling starts to fail I"d imagine.

Hmmm whatever it is, stock Vapo's and Mach's cannot handle a quad core. A custom unit tuned especially for this higher load is needed.

[{.bLanK} GoD]

But i have heard Vapo's under the load tester sounding like a deep fryer, PC Ice units too.

On what kind of heat load?
I imagine if you place a MachIIGT on a P133, you would get flood back.

What do we know for sure?
a) LS's and Mach II's work great under a P4, opty, conroe range of heat loads ect
b) They cant handle the jandal under a quad due to some of the highest heat loads produced by cpu's we have seen yet.
c)Solution to tuning a phase change rig to a higher heat load than it was previously running is More refrigerant i.e shorter and/or bigger i.d cap tube.

Walt was online 2 mins ago. Correct either or both of us Walt.

[n00b 0f l337]

I use a load system that shows accurate wattage at variable AC current.
200watt load cell in a block with mounts, controlled by a variac, plugged thru into a kill-a-watt. The cell goes as high as 275watts.

a) yup
b) yup
3) yup but more refrigerant into the evap at any given point is more precise.

With old systems we can get the heat load under control, but the temps will be higher. So is larger systems the only way to get the temps of the past?

[{.bLanK} GoD]

So is larger systems the only way to get the temps of the past?

I guess so.

If we look at a danfoss NL-11F for an example
At 180 watts (which is about what my over clocked 650 puts out) it is rated for -30°C
At 274 watts (which is about what an over clocked quad puts out) it is rated for only -23.3°C
That's on R134a btw.
And maybe the condensors on the commercial units are boarder line for 180 odd watts You must admit they're pretty dam small.
If the condensor can't condense the hot gases properly, You'll be fighting a loosing battle tuning the cap tube. IMHO


a) A larger condensor to dissipate the extra heat load
b) A more powerful compressor because more energy is being shifted

[n00b 0f l337]

I'm working out a SC12mlx with a condenser around the same size as your beautiful home made ones.

[{.bLanK} GoD]

I know there is a way to calculate the capacity of a coil, but I'm dammed if I know how
A wild stab in the dark guesstimation just by looking at the sizes of a Vapo condensor, my guess is they are good for 150-200Watts max.
My home made jobby, (as long as it does actually work properly) my guess would be around the vicinity of 1kw. probably more.

[n00b 0f l337]

Mhm mines got an effective fin area of 8" x 8" x 2".

[Gray Mole]

After reading some of the threads on Quad cores, at least Intel ones, from 2 of the units that Jinu has out there, I can estimate that we are NOT looking at 275 watts of heatload.

I'm not sure where you're getting your numbers or if you're pulling them 'out of a hat' but unless you have a heatload tester capable of 300 or more watts that's completely variable (which I do) then you have no frame of reference.

Both of Jinu's units, using 402a or a blend including it, appeared to be pulled down to -30 or so, under full load, Quad core Intel, longterm load.

That's only in the region of 230 watts, considering the compressor he's using, the condensor, etc.

Besides that, the information about simply 'adding more refrigerant' or 'shortening the captube' is NOT right. You WILL get more capacity out of it, but you'll also be shortening the life of the system due to liquid floodback, or worse, the possibility of actual physical damage due to overcharging.

There are 3 dimensions to phase change and you're overlooking that.

To increase the capacity of a system safely, you need to either physically or thermodynamically increase the system volume.

If you do this correctly, you will never have liquid floodback.

The addition of a small heat exchanger and a desuperheat coil is normally enough to add the needed volume and thermal interference to allow for increased tuning of a system that's been designed for 200w or so. The only reason you would 'need' a larger and/or more efficient condensor is to allow for a more aggressive gas such as 402a to be used. If you were to keep 404a in a system like a Mach2 and just add the parts as stated, to the required level that allows for a combination of shorter captube (to approx. 250w or so) and matched refrigerant charge, then you will end up with a system that's correctly tuned without danger of compressor or actual physical damage.

People can say what they like about VapoLS and Mach2 systems, but they are very precisely engineered to deal with the 200w they are rated for (yes, sometimes they can fall off just below that) and give the best life expectancy possible.

If we are to do equally well with custom systems or capacity upgrades on these retail systems, we need to look in the same direction, with correct tuning and configuring to give an equal level of quality and durability to our systems.

Cheers

Gray

[stone_cold_Jimi]

Seeing as I use an LS and want a quad core, I'm interested. Have we any data on volts / frequencies / heat output for these chips? At around what OC is the 200W capacity reached?

[Drag]

will an prometeia (nventiv) mach2gt hold an qx6700? i think so..

[Gray Mole]

Yes and no.

What we're seeing is a far higher rate of heatload increase than with other cpu's. This is to be expected, but it makes the challenge of designing a phase cooler, or modding an existing cooler, that much more involved.

At stock speed and vcore, a mach or vapo will handle the load.

Even with an overclock and some additional vcore, it will.

Figures of late are showing, however, that when pushed farther, and over long high load, Quad cores are pulling into regions that the Mach and Vapo weren't built for.

The original LS Vapo was made for 240w and would be an ideal solution for those who prefer a retail product. Perhaps they will decide to offer that as an option again for the LS, even though it's overall temps wouldn't be as good, at least those buying into quad core and phase cooling could have a guaranteed option.

Cheers

Gray

[Drag]

the mach2gt is very different then the mach2

[n00b 0f l337]

the mach2gt is very different then the mach2

Not so much so.

As for liquid slugback due to shortening the captube, I use accumulators whenever I can find the space.
As for your guess on the wattage range, theres no way to predict it but I do think when people begin pushing very large overclocks, like people like to do after buying a phase unit, the wattage is definitly going to be higher.

[Pete]

Intel has the thermal info if you were to look there. But it would be about x2 Conroes really

[Gray Mole]

I estimated the wattage range based on what I've been finding on the load tester in systems very similar to those currently running on Quad core CPU's.

The Mach2 and GT are very similar, though the gas used is 134a and 404a respectively, the tuning is very close. I've found that early Mach2's are easier to tune for higher loads, but the captube is completely wrapped, where the later GT's are only partially so. The combination of subcooling and heat exchange work well.

I built a load tester on a power supply capable of up to 1200 watts. The current tester itself is only set up for up to 300w, but I could change that if there were a need for it.

An accumulator can help, but in very small systems it may not be enough. Increasing the heat transfer from the captube by soldering it externally, or making a small SLHX in the return circuit, is far more effective. I find a desuperheat coil also helps in that it balances the system and allows for more volume in the high pressure circuit as well.

Gray

[n00b 0f l337]

I definitly agree with you Gray.
I'm considering brazing/solder the captube on, or adding a SLHX, but if the SLHX isn't something you can buy over and over, its not going to be very reproducable.

My load tester can go to 300 watts.

[s7e9h3n]

I don't think there's enough attention being paid to the evaps that are currently in use (especially in the MachX's). With quad cores, we're dealing with a much larger contact patch while our current evap designs generally have the refrigerant exiting the cap tube @ a pinpoint area on the baseplate......