Bit of an odd one this..............

[vega]

As I currently use a cheapo bog standard cpu fan for my athlon 1.7 XP, it makes quite a bit of racket but I've never really had any problem with this.
However, over the past few days, its started playing up big time - whilst using the computer, I find that the whine of the fan 'rises and falls' (normally, its just a steady whine) indicating changes in revs and simultaneously, the graphics become corrupted, usually when the fan slows down.
More often than not, the fan will speed up after a while and the corruption stops but on some occasions, the screen becomes obliterated with cross hatching, errors and is totally unusable - the only course of action is usually to reboot.
I guess that the fan slowdown may be causing the cpu to overheat and create the aforementioned errors - as I'm in the process of purchasing a copper block (slk? 700), I'm hoping that this will alleviate the malady but can anyone offer any insights into this as I MAY be wrong???!!

 

[Nic]

This certainly sounds like the cpu fan is on the way out, but it may be slowing down/speeding up due to voltage fluctuation, which could mean that either the PSU is going bad, or that the mainboard voltage regulator circuits are going bad.

Please don't panic just yet, as I'm only suggesting possibilities at this time. What I'd suggest you do is have some sort of voltage monitoring software running on your desktop, making sure it is set to update every second, and observe the voltages when the problem occurs.

This will tell you whether the cpu fan is changing speed because of unstable voltage, and if you don't see voltage changing, then it is likely just a worn fan that is the problem.

 

[vega]

I forgot to mention that I've already replaced the first fan (which was exhibiting the same problems) with the current fan and so far, both are exhibiting the same traits - gigabytes hardware monitor confirms that the speed does rise and fall and also, voltage readings fluctuate every few seconds - even as I'm typing this, the fan speed has gone down and I've just lost my screen!

 

[Nic]

Take a look at this post ...

mobo problems beyond belief

In your case I would also try swapping the PSU, or getting a meter to measure the output voltages and see if they also fluctuate.

Alternatively, observe the case fans (directly connected to PSU) to see if their speed changes when the problem occurs. If it doesn't then it looks like your mainboard is dying, otherwise it is your PSU that is dying.