Notes on P5B vs P5W-DH temps - why only Core Temp matters

[davexl]

Some notes after putting together 3 new systems in the last month or so.

CPU temperature as reported by the motherboard is almost meaningless to compare to other systems, even of the same model.

* P5B Deluxe reports CPU temps roughly the same as Core Temp

* P5W-DH reports CPU temps on average 18 degrees cooler than Core Temp edit: Early rev P5W with 6600

* Later rev P5W + 6400 = 9 degrees cooler than Core Temp

* both P5B and P5W systems begin to throttle exactly 3 seconds after hitting 82C Core Temp. Core Temp, calibrated or not, is reading the sensor that matters.


(all measurements at 22.5C ambient, average stable temps after 20 mins) All systems measured without any use of Rightmark, CrystalCPUID or SpeedStep. Both Systems with Intel 6600 C2D

Saving power while overclocked: (replacing SpeedStep)

* early revision P5W reports CPU temps 4 degrees lower than later revision. (tested with same CPU, fans and case)

* P5W + 6600 can drop 3C idle temps by using RightMark CPU Clock or CrystalCPUID to drop Multiplier from 9x to 6x (keeping same voltage)

* P5W + 6600 can drop 7C idle temps by using RightMark CPU Clock to drop Multiplier as well as throttle using ODCM.

* P5W + 6600 can drop 15C idle temps by using RightMark CPU Clock to enable C1E as well as throttle. (Drops Voltage to 1.1v – use with caution when overclocked – use in combination with ODCM throttling) This does not work on P5W + 6400 => crashes due to less multiplier options.

* P5B - Rightmark or Speed Step has no temperature effect whatsover that I can find. Dropping multiplier or throttling does nothing. Given that Idle CT temps are 10+ cooler than the P5W this implies that something is already enabling power saving, even with all C1E, SpeedStep disabled in BIOS.

A lot of this is already known and discussed, but I thought I would add my experiences.

All temps at 22.5 ambient, and measured by digital T-Balancer thermometer.

P5W-DH –67MOAG – 1.65v vMCH max revision
P5W-DH –68MOAG– 1.85v vMCH max revision
P5B Deluxe Wifi – 1.03G revision

[Truckchase!]

Bravo.

[JoeBar]

My P5B shows lower temps than CoreTemp and TAT.

[Mykou]

Nice work davexl

[davexl]

Thanks guys, it's not info that gets a lot of people hot and bothered (ahahaha) but it is interesting to me.

JoeBar - by how much? I take it that is with the 6400 in your sig?

My 6400 in my later revision P5W reports 9C cooler than CoreTemp.

[Millyons]

my p5B temps are the same as yours, almost the same when idle and around 4c higher with probe when under load

[Yoxxy]

Nice to see that someone has finally posted a well put together and orderly graph of how core temp works. I still question how the DTS is calibrated, as having multiple processors on phase core temp reports many different bottom temperatures. Meaning one was at 2 all the time another 5, another 10, another as high as 15. They do not fluctuate with voltage or load it is just the minimum temperature shown. Kind of crazy.

[NO1B4ME]

Thanks guys, it's not info that gets a lot of people hot and bothered (ahahaha) but it is interesting to me.

JoeBar - by how much? I take it that is with the 6400 in your sig?

My 6400 in my later revision P5W reports 9C cooler than CoreTemp.

Nice post. Pretty informative info .

[davexl]

Nice to see that someone has finally posted a well put together and orderly graph of how core temp works. I still question how the DTS is calibrated, as having multiple processors on phase core temp reports many different bottom temperatures. Meaning one was at 2 all the time another 5, another 10, another as high as 15. They do not fluctuate with voltage or load it is just the minimum temperature shown. Kind of crazy.

So you are saying at very low temps the sensor reports garbage? That could be a problem. What happens to the motherboard CPU readings, do they still scale ok?

[Ziwro]

İntel Core2Duo E6400 || ThermalTake BigTyphoon || Asus P5B-DLX || 2*1GB team Xtreem DDR 2 800@850 ||

This is my new system, i overclocked it.

1.5v 425x8 = 3400mhz

Dual ORTHOS Full Load : 65C
Dual Spi Full Load : 55C

Temps are normal ?

Sorry My English

[JoeBar]

JoeBar - by how much? I take it that is with the 6400 in your sig?

My 6400 in my later revision P5W reports 9C cooler than CoreTemp.

Idle: Onboard -> 32'C
Core Temp -> 39'C

Load: Onboard -> 50'C
Core Temp -> 59'C

Yes, specs are shown in sig.

[triggerc]

Davexl, can you give me a little step by step direction for enabling C1E as well as throttling with ODCM in rmclock? I'm kinda confused right now.

[davexl]

Davexl, can you give me a little step by step direction for enabling C1E as well as throttling with ODCM in rmclock? I'm kinda confused right now.

Right click and enable profile Performance on Demand
Under Profiles Pages, enable and tick every box in the P-State Transisiton and Use Throttling (ODCM).

This way when you enable C1E on the advanced CPU settings page, you are running as a slower speed when the CPU drops voltage - important when overclocked that your lower multiplier should not be more than what 1.1v is capable of. (hard to test as the P5w won't set manual voltage below 1.2v)

(The above is speculation to explain why one machine with a 6400 should crash and the 6600 be fine)

[triggerc]

hrm, so i can't set the lowest multi voltage to 1.2 or 1.3 then?

[davexl]

the voltages do not work - can't set them, so you can only set multipliers...

[triggerc]

damn, hope my e6600 can handle 400x6 at 1.1

[davexl]

But that is the beauty of throttling using ODCM - it will be doing a lot less - My 3.60GHz drops to about 1.1GHz

[china]

My P5B shows lower temps than CoreTemp and TAT.

And my P5B Dlx shows about 10 degrees (celcius) more than CoreTemp and TAT. Talk about consistency...

[davexl]

And my P5B Dlx shows about 10 degrees (celcius) more than CoreTemp and TAT. Talk about consistency...

Heh, yeah. What CPU?

[china]

It's a E6400 week 29, A-batch. Running at 8x375.

[Millyons]

one thing i noticed on my P5BDlx......when running dual orthos probe is showing few c higher than core temp, but running any other apps (including TAT) and even loading the temperature to higher levels probe shows few degrees less than core temp