Why does my fan speed vary so much?

[floydianSchlip]

I have a "cybercooler" fan that came with my motherboard. I use PC Alert 3 to monitor cpu temp and fan speed etc. When I boot up fan speed
settles at around 3100 rpms but after about an hour or so it tends to slow down to about 2570, where it stays. It makes a very dsitinctive sound
when it's slowing down. I have ordered a Global win FOP-32-1 because my cpu temp was also a little too high (45 - 57 C). Is there any other
explanation for this other than a poor quality fan?
My chasis temp stays constant at around 25c.

 

[mcvan]

Is this a fan part of a CPU cooler, a case fan, or what? You don't say!

It could be your fan -- maybe its bearing is already gone!?

You don't mention your case power supply. Could be that, going up/down in voltage, if it's poorer quality.

It could also be that your AC supply (either the circuits in your bldg or in your area) is bad. Does it happen more at certain times of the day? Try plugging your computer into something like a UPS (AC-powered battery) to isolate it from the main AC line. If your fan doesn';t act up after that, then you know.

But most likely, it's the fan, whatever it is used for...

 

[aznmoshboy]

I think a poorly made fan is your problem...and I've never heard of that fan before either...

 

[floydianSchlip]

The fan in question is my cpu fan.
I have a HIPRO 300W power supply.