It's not a driver issue, You're PC's not even getting that far.
When the issue occurs is your PC beeping at all?
Your PC is failing during whats called the POST, Which is where it first starts up the very basics you PC needs to run. If it made it past POST you'd get keyboard lights.
This means either your memory, Processors, motherboard or video card is bad. We've managed to rule out Video card by testing it in another computer.
Processors actually go defective only very rarely unless you overclock em. it COULD be the proc, but I highly doubt it.
Try reseating the memory, or even better, testing it in another PC, or with a stick of memory you KNOW is good.
If it's not the memory, I'd honestly look into replacing the mobo, because well... those bastages go bad quite often.
You can't rule out overheat because the Graphics Card worked in another PC, because any number of parts can overheat, but I'd rule it out because it doesn't take a "Week" for the PC to cool..
Also I'm ruling out the PSU because I've never seen one have intermittent issues like this PC is.
And don't take it to best buy or Frye's, they'll hire any idiot to be tech, trust me on that one. You take it to a tech, take it to something small and local, they usually have guys who know what they are doing.