High fan speed
 

Had a bit of a search and couldn't find anything closely related to my issue

After 5 years of normal runnng, my PC has suddenly been running the cooling fan at high speed from startup, with occasional spooling up/down for no apparent reason. Everything else seems to function normally/well

Took the side off the machine and had a gentle hoover round inside.....although there wasn't anything obviously clogged up with dust.....is there a thermostat somewhere governing fan speed? and where would I find it? Can it be replaced if needed?

One of our machines did this and shortly thereafter the power supply failed. I don't know whether the high fan speed was the result of the imminent failure or the cause of it, by drawing more power, but you may wish to get that possibility looked at.

Given the price of a fan - replace the fan & see what happens.

Try this SpeedFan - Access temperature sensor in your computer

And this set up guide Using SpeedFan to automatically control your PC’s fan speeds » unitstep.net

Which cooling fan, case or cpu ? If the case, does it have its own little temperature sensor ? Also if you look in the bios there are usually options there as to whether the fan is throttled or not. New bios loaded or settings changed ?

+1 Do the easy thing first, go into the bios & check to see whether or not there is a temperature fan control setting disabled. If it is, enable it. On my system, it's called q fan control & enables the bios to speed up or slow down the fan according to the cpu temperature.

"The boy" came round this afternoon and had a look at it . I'm not as techie as he is....and he did some magic stuff with the bios (far too esoteric for me) to establish that the CPU temp was 79C.....his diagnosis is that the thermal interface compound (?) has broken down over time and needs replacing....which he has undertaken to do.

Well, if that's what's up, it's a five minute job. The paste is smeared on the rear of the cpu & helps conduct heat from the cpu to the vanes on the cooler & the fan itself blows air over those vanes, cooling the whole shebang.

It's a bugger to wash off if you get it on your fingers mind.

I'm told that iso propyl alcohol....I think that's what he called it, is the stuff to use as cleaner.

Vodka works as well :E

A friend runs an hotel in the Alps. The bar has crappy laptops on wifi for the punters & he uses Vodka on the old trackballs to great effect.

Isopropyl alcohol does a much better job on heat sink compound than vodka etc. Don't get either (IPA or HSC) on your fingers if you can help it. I use a matchstick to smear HSC around, and rubber gloves anyway.

70°C is a tad hot for a PC chip. The diagnosis sounds right.