Subject: High BIOS temp, low OS temp
By: Ray (IP: 86.128.146.*)
Written on: 28-03-2008 03:01

The other day I rigged up my testbench & noticed that the CPU temperature displayed within the BIOS was .... ummmmmm ... a bit warm. I am aware that the BIOS semi-stresses the CPU i.e., it runs warmer than shown within an OS either at idle or short-stress Burn In.
Also, F10/Exit and save didnt work - the BIOS screen hung.
I refitted the same CPU etc with fresh thermal paste, same result.
I trust the BIOS temperature every time ... but I ALWAYS do a fingertip test on the heatsink in this situation. This arbitrary fingertip test ensures that nothing insane is going on. Result - nothing unusual.
Within Vista Ultimate at idle, Sandra showed temps close to normal and Burn In showed lower maximum than the BIOS temp.
I then removed the CPU & fitted a different, low baseline spec CPU. BIOS temperature & Vista temperatures were as expected i.e., cool.
This motherboard has a soldered-in BIOS chip and the latest (only) BIOS revision - so no upgrades are possible.
Certain motherboards/BIOS revisions/CPU combinations will show high BIOS temperatures & possibly high temperatures with long-running CPU-stressful applications e.g., games, Folding (fill in this space). etc, etc.
BIOS revision has not kept up with CPU development.
Step to a different BIOS if you can. Otherwise, a different CPU or motherboard is required - don\\\\\\\'t blame the heatsink if there\\\\\\\'s a mismatch!
Well, this may be a coincidence but I think not.
With the mismatched CPU/BIOS setup ... when I tried to change ANYTHING in the BIOS then save the changes via F10/Save and exit, the BIOS hung. Restarting showed the changes WERE implemented & saved. And if I exited the BIOS having changed nothing F10/Save and exit worked flawlessly.
I thought the motherboard/BIOS was damaged, so I changed to the low basline CPU .
With a matched CPU/BIOS setup - F10/Save and exit worked perfectly. And, as stated, CPU temperatures are cool.
Also note:- this motherboard/BIOS version runs top-end CPUs flawlessy.
The culprit was a late-spec CPU that the BIOS simply had no way of coping with. The fact that the combination ran at all was OK but the BIOS issues showed up this mismatch.
Keep reading THG. There are loads of solid, commonsense, hands-on real-life, practical advice here.
Other info:-
Motherboard - BCM BC875PLG2 (industrial spec).
Warm/late-spec CPU - 3.0 Prescott sSpec SL8JZ (the low TDP version, G1 stepping)
Low baseline CPU - 2.4 Northwood sSpec SL6WF
Top-end CPU - 3.4 Gallatin sSpec SL7CH
Heatsink - solid copper 1U with 70mm generic fan (server spec)
Thermal compound - ShinEtsu Microsi MPU-3.7

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