I've been using the same desktop for almost 10 years now.
It was top of the line when I got it, and overclocked, with a custom compiled kernel. So it did a good job of lasting. But it is very very slow by todays standards, and no tricks to squeeze out more speed are going to help any more.
I just dropped $3000 for a new custom system though. It will be an i7-6700k! all a-list parts, and a solid state drive. It's gonna be crazy.
But I have to wait a couple/few weeks for all the parts to get in. Busy time of year and all.
I can't fucking wait.
Mine started doing that a couple years back.
But after I kicked it, out of frustration, it stopped the noises.
Sometimes you just need to let them know who's in charge. I got another 3 years, and it's still going.