Cooling Core temps lower than CPU temps??

That title sounds confusing I know

Both Everest and Speedfan 4.29 show my 'core temps' lower than my CPU temps.

Speedfan only has one core temp listed that has appeared since I installed 4.29 and the 'core temp' (which apparently is a reading directly from the diode in the core itself) is approx 5-6c lower than my cpu temps.

Everest shows the temps from both diodes (i.e one in each core) and whilst they are within about 2-3c of each other they are also 5-6c lower than my cpu temps.

Obviously the CPU temp is being reported by a sensor on the mobo under the socket so wouldn't it make sense that my core temps should always be hotter? not cooler?

speedfan reports:

CPU idle: 35c
core idle: 30c

CPU load: 48c
core idle: 42c

everest:

CPU idle: 35c
core1 idle: 32c
core2 idle: 30c

CPU load: 48c
core1 idle: 44c
core2 idle: 42c

 

Motherboards can be notoriously unreliable in reporting temps --they are simply not very accurately calibrated. As such some motherboards over-report. My K8T Master-2 Far for instance, consistently over-reports CPU temperatures by 2 degrees C when compared to on-die CPU sensor temperature reports.

Comparatively speaking that is not too bad; some motherboards can be 5 degrees out. For obvious reasons, it is always safer if a motherboard over-reports rather than under-reports, so I suspect this arrangement is deliberate, to compensate for any inherent measurement errors that might underestimate temps.

Another problem is one of resolution; temperatures tend to be rounded off to the nearest 0.5 degree. Depending on what both software and motherboard measure, there will therefore be an additional measurement error discrepancy of up to 1 degree between them.

 

Yeah, Nexxo explained it quite good...

But I know in Speedfan you can adjust the calibration, somewhere in the config menu.

 

Do you suggest then, that the core reading is more likely to be accurate, as this reading apparently comes from the diode on the core/s itself?

It seems rather low, not much above ambient at idle.

 

Depends on what is your ambient room temperature, and what CPU we are actually talking about (and what cooling). If it is a Core 2 Duo for instance, maximum safe temperature is about 60C. That gives you not so much leeway and makes an idle core temperature of 30 to 32C pretty likely. A small test on silentPC review for instance measured a difference of only 12C between room and idle temps on a Core 2 Duo using a Scythe Katana heatsink with 92mm stock fan.

BTW another easy, non-flashy way to sample core temps is Core Temp. Use it to calibrate Speedfan.

More info on different problems with measuring CPU temperatures with external sensors here: http://mikewarrior.freeservers.com/

 

Cheers Nexxo,

Thanks for the heads up on that core temp prog, I was under the impression that it could only detect core temps on intel chips.

Having run it, it gives me exactly the same result as everest, and it would appear that speedfan is using the sensor of core#2.

If these core temps are accurate, it means that my chip is running a lot cooler than I thought!

Yay for today!

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