Months ago my sort of dream computer was built, it was working fine until my video card (XFX 5850 Black Edition) went defective on me. Ever since then its been a nightmare. When it went defective I RMA it. i thought problem solved but ever sinced then my video cards were constantly on becoming defective so after the 2nd RMA they sent me a different one (XFX 6870), by that time I was fed up and bought a different one (Asus EAH 5850) thinking that when they would send me a good card so I could crossfire it. So to speed things up my PC freezes on me 5-10mins whether I'm gaming or not. I am open to any suggestions. Note: Both video cards work fine. I bought cheap memory sadly because it was getting kind of getting expensive (I also did a memtest86 but only one works) but I bought some corsair vengeance I also bought a new mother board because I was told it was defective. I can't even update because of freezes, is it the motherboard or power supply...?? Please Help. I don't know anymore options.