I bought a barebones pc of internet around 4-5 years ago and I don't even know what motherboard it is now and for last several months the cpu fan has been making more and more noise. Now this weekend I think something is reaching the breaking point. When I power up the computer the cpu fan speed varies wildly from low to high and it isn't periodic...it seems pretty random. After a few minutes the fan seems to calm down a bit, but still is noisy and it will slow down and speed up regularly. Sometimes when it slows down it does or nearly comes to a brief stop. I'm beginning to smell that wonderful smell when electronics starts to get too hot and I just power off computer at this point. I have a few questions on how I should deal with this. First, does it sound like a cpu fan problem, power supply or something entirely different. Second, I can try to replace fan since it is cheap enough, but I don't know how to tell what fans out there is compatible with my motherboard/cpu. Third, I suppose I could afford another power supply as well, but just like the fan I don't know what will fit/work with my computer. My computer specs from what I can tell are: power supply is 400W 1gb amd athlon 512mb pc133 ram geforce fx 5500 8x agp 40gb hard drive win98 Thanks for any help on this.

You'd better determine which fan is making the noise & fix it ASAP, or you're gonna be replacing a lot more than just a cheap cooling fan. I suggest that once you know which fan it is, do NOT use the PC until you get it fixed...unless you relish the idea of replacing the CPU, motherboard, AND power supply?

Yes replace the fan right away! Just get a fan that is the same physical size. They are pretty much compatible other than that. Do yourself a favor BACKUP!

Better yet, remove the fan and take it to wherever you want to get the replacement from. Do yourself a favor BACKUP!

It's the cpu fan that sits on top of the heat sink on the cpu. Thanks for your recommendations. It's only been smelling this past day or two and when I did smell it I did turn off computer right away. Hopefully the fan is all that needs replaced.

AMD cpu's don't do well when they get hot. Follow ham30's advice and take the fan with you to find a replacement. Don't remove the heatsink from the cpu, just undo the fan.

if you are really desperate (like you live 100 miles from a supplier) you can do this: remove fan from pc. peel off the sticker/label from underside, this usually reveals the spindle. spray into spindle hole some WD40 (that's what its called in UK). spin the fan around a lot to work it in. when spinning freely put in a blob of thin oil (type you would do a bicycle chain with) (NOT VEGETABLE OIL AS THAT OFTEN TURNS TO GUM WHEN HOT EVENTUALLY). Spin fan to work it in. Now reassemble - MAKE SURE THERE IS NOT SO MUCH OIL THAT IT SPRAYS OUT . This sometimes makes them work fine for a very long time, and sometimes not so long - depends how bad it had got. Fans vary in design, sometimes there is a rubber plug to be removed under the sticker, sometimes no access to spindle. Fan is held to hinksink by 4 crosshead screws(usually). when unscrewing, do not press down too hard in case it causes too much pressure on cpu.