I know you're getting tired of seeing pictures of dusty computers, but I can't get enough of this stuff. What kind of environment does a machine have to live in to get so thickly coated with crud? Imagine what the users lungs must look like.
The thing about most of this dust, was that it wouldn't even lift off with the 5HP shop vac. I had to use compressed air at about 50psi to get it to budge. It seemed to be mixed with something else that made it slightly sticky and clumpy, but I don't think it was cigarette smoke because there was no smell and no yellowing.
yucky... but i'm guilty of same.
i gotta tell you, i have tried regularly to keep our desktop clean, and it ALWAYS accumulates that kind of crud.
it's so bad that i've elevated the hard drive to keep it off the carpet, but to no avail.
any suggestions?
Suggestions
Try keeping your PC up on the desk if you can. Or, if that's not possible, and you have a way of attaching an old pantyhose over the mesh fan holes in the case in the front of the machine, that will at least block the bigger chunks of dust and animal hair that tends to get suck up into the PC. You can then take the pantyhose off regularly and hand wash it in the sink, hang it to completely dry, and then reattach it.
Also, if you find the machine is dirty when you open it up every 6+ months, try cleaning it out more frequently. Especially if you have animals and are a smoker.
Fun
I want to see a dead animal in one of these machines.
Spackle
That spackle looks downright cancerous. I went into the bathroom at work and the side panel was up. When I came out, it was laying on its side exposing these two views. I almost lost my lunch. I was seriously worried about your breathing while you were cleaning it out.