OK guys, this should be the correct place to post this.

Recently I have been hearing strange sounds inside my PC. It sounds like a fan, kind of slowing down and almost churning, before sounding like starting up again and the sound goes. It's not a clicking or anything like that. I removed my case of my PC to hope to find where the sound was coming from, and then it stopped happening, and it dosn't happen as much now. It either happens a few times in a short space of time, or not at all for a long time, so it's rather annoying sitting there waiting for it to happen, only to find it dosn't.

However, I have now had 2 random restarts in the space of a couple of days, and they don't happen when my PCs just left running, but when i'm about to do something, like just after clicking on a web link, and just now when I opened a folder. I get no error message although there are logs in the Windows folder which say the time it happened but I have no idea what log is best to look at, as some arn't very helpful.

Any ideas what this could be?

I'm quite sure the sounds and restarts are related because I never got any random restarts before the sound started.

it sound like u may have a cpu fan or case fan failiure which is causing the pc to overheat. check all your fans are fully functional.
secondly it could be a virus that may be slowing your fan speeds down.. i know this seems strange but it is true.. believe u me. try running a antivirus program and see if it pulls anything up.
if not try replacing the fan that you think may be the problem. fans are pretty cheap.

Random shutdowns could also be cause of a faulty power supply which could make the strange sounds.

I don't know if this has anything to do with it, but an Asus Probe the Power fan is unticked and when I tick it is flashes the message - power fan below threshold, and it flashes 0 where it's meant to say it's status. I can feel air coming from the fan if I put my hand behind it though...