my CPU makes a whirring noise everytime I boot it up. It continues till the PC boots and stops soon after. If I tap the cPU cabinet it stops. This has been happening for over a year and I can't understand why. what could possibly be wrong? Is my computer in danger of crashing?

Check the cooling fan to see if any cordsare touching it.

Probably the bearing is worn on one of your fans. Depending on which fan it is (power supply fan, heatsink/fan or case cooling fan), you could fry your CPU if the bearing seizes & the fan quits working. Fans are cheap...figure out which one it is & replace it ASAP!

Nope. Yo are talking about the WHOLE computer, aren't you. The CPU is the little processor inside the machine. If your unit is making crackling noises while it boots up, and then it stops, it may be the way your hard drive is seated inside your machine. If anything is loose on the computer, ie the side panels, or something meatl, then when the hard drive is active, it can cause vibrations in the machine which are enhanced by the loose piece! And when the computer has booted up, the hard drive stops working and all the vibrations stop. Do the vibrations start again, when the computer starts a program?

I go with Dhiren and Jam . . . If you're certain that the noise is coming from the location of the CPU, then it's probably a small cable that's brushing against the fan - dirt interfering with the proper operation of the fan - or a bearing that's gone. Before posting here, you should've removed the cover or right side panel (when viewed from the rear of the unit) to see for yourself more precisely where the noise is coming from. Sometimes cheaper metal cases can cause vibration noises too - that stop when you push or tap (bang???) on the housing. XxxFrancisxxxUSA has a point with the hard disk too though. However, based on what you've written, it sounds to me more like a fan or case vibration issue. Hey Intel, AMD rulez!