[Rumor]

It sounds really loud, like something is perhaps vibrating. It recently started but I turned off the G4 and it went away. Until a couple of days ago, now it starts not too long after booting.

I opened the case and decided to wait for it to start, as it sounds like it may be coming from the fan or perhaps power supply (though I have never heard of a power supply making funny sounds). Oddly enough, if I blow on the area with the fan and power supply, the noise starts up.

So if it is the fan, where can I get a replacement?

[idykenano]

My guesstimate would be that the fan is coming loose a bit, and when it runs it is going off kilter and shaking the case, etc.

[DrBoar]

If it is the big 120mm fan for the case the easy way is to replace it with a quiter fan that is running of a 12V tap (the same kind of connector as hard disks) Other fans are more diffcult to replace. Try booting with the fan blocked with a pen or finger. The computer can run safely for a while without a fan. The small fan on the graphic card can make an awfull high pitched sound, the big 120mm fan is more of a midrange rattle.


But the first thing is to find out what the offending part is.