Very Random Freeze Ups (New Build)

Hello all, I've recently built a new computer and before I address my problem, here are my specs:

Intel Core i5-2500k 3.3Ghz
Asus P8P67 Pro
g.skill 1333 4gb (x2)
Corsair TX650W
EVGA Geforce GTX 460 768mb
Samsung Spinpoint F3 1TB

I know the gfx card and PSU works because I've used it on an old computer for many months now. So, the first issue was getting the computer to boot up properly: it wouldn't. But it was 3 in the morning so I called it a night. After coming home for school over 12 hours later, computer magically booted up again. I proceeded to install W7 64 bit and all was going well. As I was installing drivers, the computer would freeze up. The times it would freeze up would be random: at BIOS, while installing drivers, or simply being afk. I've googled around for solutions and the closest thing I found was this site. I tried everything in post #14 also by the OP. However, this still didn't fix the random freezes.

As of now, I am trying out each RAM stick by itself and it has been going at a record 30 minutes. The second stick lasted roughly 15 minutes. Additionally, during the 2nd stick trial the screen flickered and momentarily I saw an error about the graphics card. I will run some memtests and update on that but I want to know your opinion on this matter.

Thanks in advance.