Asus A7V333 CPU Temperature Reading

[Bing Fung]

Lex, I know your runnning a simular set-up, could you tell me what your Asus Probe CPU temperature is at?

Currently mine is reading 57-60C @ 1898 mhz (13x146) This seems a bit high to me, however even at stock 2100+ XP speeds, the CPU reads somewhere around 55C. Core Voltage is at 1.75V.

I had heard the diode reading can be different than themistors on the mother board. It seems 40-50 C is the norm for people with thermistors, yet my Asus Probe stated the stock speed temps are higher than that at 54-55C.

Is this because the 2100+ runs hotter?

Could it be a diode bias?

Maybe I should re-mount the HS?

My case seems very cool to the touch and the case temperature is at 30C. There are no hot spots in the case. The heat sink is luke warm to touch and the air coming from it is relatively cool to warm. I'm sucking air through the heatsink as Alpha recommends rather than blowing through the heat sink.

I have enable Qlogic and noticed the CPU fan spin at 3200 when the system is just started and then most times it seems the A7V will run it at around 2700RPM. Thermo shut down by default is set at 80C so it seems as if I'm with in the Asus's operating window.

I'm suspecting that the on-die diode maybe giving a more accurate or biased CPU temperature than the motherboard thermistors. Typical MB themistor temps tend to be in the 40-50C range, where as the on-die diode reading of my Asus is at 50-60C.


Specs...

Asus A7V-333 RAID
AMD 2100+ XP @ 18.98 Ghz
Alpha PAL8045 / 3200 RPM 80mm Sunon Fan
512MB Samsung 2700 DDR RAM
Hercules GF3 @ 490/220 (soon to be upgraded)
2 x 40 GB Maxtor DL740 ATA 133 in RAID 0
1 x 40 GB Quantum FireBall ATA 100 Backup Drive
Pioneer 106s DVD drive
Plextor 24x10x40 CDR-W
Intel Pro 100 NIC
SB Live Platinum 5.1
Enermax 431W ps
Lian-Li PC 65

Here is a picture of the rig




Bing

[SiliGoose]

Beautiful system, Bing. Still one of the cleanest case mods I've ever seen.

Is this because the 2100+ runs hotter?

It should be cooler than, say, a Thuderbird due to the smaller die. My OC'd temps (albiet on a totally different mobo) are around 44 C.

Where is the temp sensor on the Asus? Is it touching the bottom of the CPU? Any stability issues? How far have you OC'd it?




-Sili

[Bing Fung]

Thanks Sili

Actually the 2100+XP is not cooler than the T-birds, it consumes less power for a given output, however it is has the highest amount of thermal output of all the Athlon CPU's : 8O

I have had it as high as 1950 mhz (150 FSB x 13), however it is not totally stable there (yet :P ). Windows will run, but 3D apps will crash to the desk top. It runs very stable at 1898 mhz 8) And that is where I'm running it.

The A7V333 uses the XP's built in temperature diode to obtain the CPU reading. This is an actual on die temperature.


OK, so after some research I have learnt quite a bit today after posting the original post....

My 2100+ Xp runs at at 55C, stock speeds with a Alpha PAL 8045 and 80mm Sunon Fan @ 3200 RPM.

At first I though this was high, however after doing some research I found that this is very close to the theoretical calculated temperature of that particular system.

It seems with the motherboard thermistor (probe mounted on the mb under the CPU) we have been lulled or fooled into thinking an AMD XP operating at 40-50C is typical, when it fact the actual on die temperature is more in the +70C range. The problem is the mb thermistor only contacts 1% of the actual CPU die and must read it through the CPU substrate on the back and outside the actual CPU die. This means a fudge factor (thermal resistive value of the substrate) must be included into the reading of the mb thermistor to calculate what the temperature of the CPU may be. This can be sketchy at best.

The XP's have a built in temperature diode that reads actual on die temperatures, however there is only 2 current mother boards that I know of that supports the diode, the Asus A7V333 being one of them.

Here is an article that discusses the Themistor vs Diode

You can calculate what your theoretical CPU temp should be by using the formula:

C/W * CPU Wattage + Ambient C = Theoretical CPU temp C

Where:

C/W = Heat Sink Rating
CPU W = CPU wattage (calculated with Radiate Get it Here )
Amb = Case temp (air measured 1" from CPU intake fan).

Example in my case is:

C/W = 0.280 Alpha heatsink rating in expulsion
CPU W = 124.9 Watts
Amb = 30C

So:

0.280*124.9+30 = 64.9 C for my 2100+XP @ 1898Mhz (165mhz OC)

Which is very close to what my A7V333 is indicating right now with Asus probe (61C).

My system is cool to the touch and very stable, so I tend to believe that what I'm reading is close to correct. As well the Asus Q-logic turns down the CPU and Case Fan RPMs to reduce noise. Currently it reduces my CPU from 3200 to 2600 RPM and my Case fans from 3200 to 2200 RPM so obviously it doesn't have a problem with my CPU at 60C.

I chatted with the author of the articles above and he indicated that 60C seems reasonable by all accounts depending on how the measurement is obtained. In my case with the A7V it is near to accurate.

Note, the Asus C.O.P. (thermal protection) is set to shut down if the CPU approches 80C by default. It would seem that I'm operating with in the expected temperature range.




Bing

[Lex]

Bing, I would have to check it and see. Actually, just no time for those other PCs lately,

Lex