Strange CPU temp jump after reboot

[5cupa]

I just finished building my new shuttle with a C2D E7500 cpu.

the strange thing is when I start the machine up after saying being off all night it always reports higher cpu temps e.g 48c. if i reboot instantly or wait a few hours etc it will report the temps as 35c. quite a difference.

If i dont reboot the temps stay stable at 48c

If i keep rebooting after the initial boot it will always read at the lower temp. no matter how many times.

any ideas?

thanks

[Blaineoliver]

Could be a wierd cooling problem, set your fan to constant 100%, and turn off speedstep and see how it changes.

[scaryjim]

Is this the temp in the BIOS hardware monitor or using a monitoring program in your OS?

[5cupa]

in windows, as the bios wont allow any throttling its like the speedstep doesn't kick in from the first cold boot...

[Badbonji]

Try updating the BIOS for the motherboard to see if that helps.

[5cupa]

bios is uptodate. no new releases.

[mycarsavw]

What app are you using to read the temps?

Have you tried a few apps to see if it changes?

Does it "feel" as hot as it's reported as being?

[Badbonji]

Try running prime95 on both occasions, could be something wrong with the sensor too. Is this a temp of one of the cores or the CPU overall?

[5cupa]

speestep still works on both boots, its just the first boot of the day is always 10c higher