I have a Dell 8400 computer about 8 months old. About Jan or Dec it started some really nasty grinding noises at startup that never cease even when the computer is, in theory, at rest. I upgraded the system bios soon thereafter and the grinding stopped altogether. I did another bios upgrade yesterday and the grinding is back and worse than ever. I flashed the bios back to the previous version but that didn't make it go away again.

My first thought is this sounds like hard drive failure, but after running the extended diagnostics provided by Dell, nothing came up. In fact the test ran quietly as well and none of the grinding noises came up during it. I did a full system hardware test following and it didn’t come up then either.

In addition to the grinding my computer is running slow and having all sorts of random things happen. Drivers for my mouse and usb wireless internet adapter have to be reinstalled constantly, and my dvdrw pops out unprovoked at random.

What else could be making that grinding noise? Is there any possibility this is linked to the processor or motherboard? That’s pretty much all the diagnostics didn’t check.

I'm not sure about dell's warranty, but is it still under warranty? it all sounds like it points to the hard drive.

It did end up still being under warranty, and Dell is taking care of it. They said it is either the HDD or the motherboard. Since they don't know which they're just going to replace both for me.

That's good to hear.