BIOS CPU temperature or HW Monitor? Which is more credible?

[nine9s]

I did a stress test on a stock 3770K system. HWMonitor showed hitting in mid 60s C on all 4 cores. Then after letting it idle for 10 minutes it showed low 40s C. I shut-down and went into the BIOS. It showed 32 C. I then immediately booted into O/S and HWMonitor still showed low 40 C.

I would think the BIOS would be more accurate. Opinions?

Any other temperature software to use?

 

[SickBeast]

In the BIOS the CPU runs at full speed and full voltage even though it's idle. In Windows using HW Monitor you're getting a more accurate idle temp because your CPU will downclock to something like 1600mhz at 1.0v.

 

[nine9s]

In the BIOS the CPU runs at full speed and full voltage even though it's idle. In Windows using HW Monitor you're getting a more accurate idle temp because your CPU will downclock to something like 1600mhz at 1.0v.

Thanks. The BIOS idle temperature is lower than what HWMonitor shows for idle temperature - from what you described, shouldn't it be the other way around, e.g. BIOS idle would have higher temperature than HWMonitor idle?

 

[ShintaiDK]

Ignore the BIOS

 

[Idontcare]

I don't know what sensor the BIOS is reading when it displays the "CPU temperature" in the UEFI, but in the case of my asus MIVE-Z the BIOS reads some sensor that has nothing to do with the on-die sensors that are read by realtemp and coretemp.

This was fairly easy to confirm because the ASUS probe software reads/reports the same temperature sensor as the bios. So I just loaded up my system, turned off the fan and put a box over the HSF to trap the heat and watched the reported temps versus the reported clockspeed (knowing the clockspeed would throttle as soon as the CPU hit TJmax).

Both realtemp and coretemp reported the correct temperature when throttling began occurring. The asus software was under-reporting the cpu temp by some 20C at that point.

 

[nine9s]

Thanks for sharing that experience about Asus not being right.

Is mid 60s with all 4 cores and 8 threads under load, okay for a 3770K at stock? It is around 28C in the room.

 

[ShintaiDK]

Thanks for sharing that experience about Asus not being right.

Is mid 60s with all 4 cores and 8 threads under load, okay for a 3770K at stock? It is around 28C in the room.

Yes. Tjmax is 105C.

On stock my i5 3570K hits 80C with Linpack and stock cooler.

 

[nine9s]

Yes. Tjmax is 105C.

On stock my i5 3570K hits 80C with Linpack and stock cooler.

Thank you for confirming. I was seeing all kinds of numbers in other threads, so was not sure.

 

[ShintaiDK]

Thank you for confirming. I was seeing all kinds of numbers in other threads, so was not sure.

First lesson is basicly to remember that silicon aint flesh and can operate at different temperatures. Also a different span in what they work best. Its for example better to run it at 90C than it is to run it at 5C if we look above overclocking. Even the optimal idle temperature is actually set to 45C in the datasheets.

 

[lehtv]

Even the optimal idle temperature is actually set to 45C in the datasheets.

That's interesting. I've got my i7-920 idling at exactly that temperature and I was always a bit let down by that, I had hoped it to stay at 40C or below.