Ok, here it is: I have an Athlon XP 2500+, which I overclocked by changing
gradually bus speed from 366 up to 400. Everything worked well, until I've
checked CPU Temperature reported or by BIOS or by Everest...

I have Idle temp around 88 C !?!?

I doubt this is valid measurement... until there is something strange like
motherboard reporting it in Fahrenfeits instead of Celsiuses...

Why?

Beacouse without overclocking the standard temp was about 60 degrees... I've
used some Volcano Cooler, then Alpine 64... and currently Thermaltake
X-blower combo.
I've run 2-hours stress test in the Everst... keeping core temp around 93
degrees... It did not burned...

Manual investigation (touching :-)) reports that no radiator, nor
motherboard around CPU are hot as shall be expected... much hotter are area
around Chipset (not mentioning it's radiator) or Graphics... Well the
heatsink of the CPU cooler is rather cold... only near bottom this is
measurably warm. And yes, I've used thermal paste.

I'm not receiving any suspicious behavior or system unstability (well, no
different or more often than before).

My MOBO is Gigabyte K7 Triton. The bios is latest version. Motherboard
temperature is reported 32-34 C...

Any suggestions?
Thank you in advance.