C2D temperature woes

[Babrbarossa]

Thanks- My new board should be here before too long, and that will give me a chance to see if it is in fact the BIOS or board.

[tomb18]

Hi,

First of all, you should make sure of all of the following:
On the CPU Configuration menu in the BIOS be sure to
Disable Speedstep
Disable Thermal Control
Disable C1E Enhanced Halt state
Disable all spread spectrum settings

Set Manual for Dynamic fan control and set them all to 100%

Now, CoreTemp measures the thermal diode temperatures. Speedfan supposedly does the same thing. Tjunction is NOT being measured, rather the thermal diode values described below: T Case as reported by speedfan ( Cpu temperature) is using the motherboard thermocouple which is notorious for being very inaccurate. In fact, Speed fan allows you to change this value. Just get the maximum tcore values from coretemp, average them, and then subtract 15C from this. Then determine what the Cpu temperature that is being given by speddfan is and subtract or add whatever is needed to give you thius temerature. It's like a calibration.

The tricky thing is that the actual way the programs determine the core temperatures is to use the TJunction temperature (which is a design spec number specifying the maximum diode temperature that can exist before the processor shuts off) and then subtracts a number that is obtained from a register on the chip that gives the diffrerence between the actual temperature and the tjunction temperature.

Both CoreTemp and Speedfan work the same. Thus if the thermal diode reads that the core is at 60C, it places 25 in the register and the program then reads this register and reports 85-25=60.

So, both coretemp and speedfan should give identicle values. However in the case of quad core CPU's, Speedfan erroneously uses 85C as tjunction, therefore if you compare the core values given by coretemp and speedfan, you will see that the speedfan values are 15C less than those of coretemp (since Tjunction on quad is 100C - a reported bug).

Nonetheless, the spec that should not be exceeded is the tcase temperature. This is specified at 65C for both dual and quad core chips and is typically 15C below the thermal diode temperatures. So having 80C on a core on your chip using coretemp is OK.

Now how concerned should you be with high temperatures?
For CoreDuo 85C shuts off the processor.
80C starts the thermal throttling (if enabled in the bios..i.e. cpu thermal control)
75 you are out of spec but not enough for the processor to start limiting itself. These are all tcore temperatures as measured by Coretemp for example. Not the BIOS or CPU temperature in Speedfan .

Now if you are seeing wild fluctuations in a coretemp core value, then something is wrong with your chip, or you have some fan speed management running. Be sure to check your bios settings. This has nothing to do with your power supply.
Heck, my power supply puts out 11.1V all of the time and the system is fully stable.

[Babrbarossa]

Thanks for the info- so what I've been calling Tjunction is really derived from tjunction but is known as Tcore- ok. Since my last post I have flashed the newest BIOS- that made the fanspeed recover to it's proper speed (2600 rpm). I have all of those things turned off in my bios already, and I know that my psu isn't the culpret.

However, late today, after I was feeling like everything was copasetic, I heard my fan speed drop again, and sure enough, I checked speedfan and it was down to 1000 again dammit! I have no idea why it's doing this, but I went back into my bios and just changed the settings, restarted and changed them all back to 100% and restarted again, and I think it's o for now. I don't think i can relax though, I'm sure I'm not out of the woods- I'm wondering if it isn't one of the monitoring programs mucking with it like speedfan.

[Shredder]

Bab and all,

I too am suffering from a mistrust of temperature values these monitoring programs are showing me, It would be nice if 2 out of 4 would match up temperature values.
These are my week worth of observations on this system I am running here.

On this Asus board with 1801 bios, when I have SpeedFan 4.32 running and open Asus Probe II , The Probe CPU temp goes to 256 C setting off alarms everywhere , Speed fan intermittantly forgets to poll the fan speeds and shows them at zero rpm, again setting off panic within...

CoreTemp - reads my Kentsfield as a Q6500 perhaps this is because I have under clocked the processor... with Tjunction at 100 C
TAT identifes my Processor as an Pentium M class.
CPU-Z - reads the processor as a QX6700

My Zalman Cooler states it is a pwm fan, so I had selected that option in Bios, The cpu fan Speed never changed, as always I had disabled any fan control in bios, manually set at Max. I changed that setting to DC (only other option) and now my fan changes rpm based on load/temp.

I found another explaination of the differences between the monitoring software, where the sensors are pulling the info from makes interpretation easier.

Core 2 Duo Temperature Guide

Note : I under-clocked the 4core while I messed around with this problem.
I am running Boinc Rossetta at 100% CPU for my Full Load testing, 76 hours continuously on this particular run.
I ran the TAT, adjusted Speed fan temperature offsets to match TAT values= Tjunction Core1 and Tjunction Core2
Added 15 Degrees C to the Core0 and Core1 Temps and renamed them Tjct1 and Tjct2 and added 15 Degrees C to Core 2 and Core 3)

Based on the speed fan adjusted temperatures and the Guide from Toms site, I am starting to get comfortable with the numbers I am seeing. today Ill open the clocks again and try the same tests.
Attached is a Full load Screen Shot with 4core underclocked

[Babrbarossa]

For some reason, now that I'm on water cooling it looks like the temps are being read properly (or closer anyway) for some reason. So are you having trouble getting you cpu fan to run full speed too?

[Shredder]

Originally Posted by Babrbarossa

For some reason, now that I'm on water cooling it looks like the temps are being read properly (or closer anyway) for some reason. So are you having trouble getting you cpu fan to run full speed too?

I was until I changed Bios setting to DC from pmw