I upgraded my build just last night and everything went fine. I replaced the motherboard and cpu with an asrock extreme4 z77 and i5 3570k. SO I put everything together, I didn't change anything in the bios, I booted windows 7 from usb and installed. Once windows was installed I ran windows update until i was update with all imporant/recommended updates. I also installed some optioal updates. After maybe 1hr the screen just froze, my mouse and keyboard, both of the lights on them went off and they didn't work when i tried to click or type anything. This happended a few times and I decided to check device manager. It showed me there was some unrecognised devices and usb controller devices. So because I coudn't use the disc I was given with the motherboard because my ODD is ide, I went on the asrock website and I downloaded some drivers that I thought would solve the missing/unrecognised drivers. Unfortunately, it didn't. That's about it, and here I am.
Check the code on the motherboard LED display when it freezes. (You might have to open the side to do this). There are a variety of numbers and letters that show up when there is an issue (Like A2 when no HDD is detected, this mostly happens within a couple of seconds within bootup, it gets detected after)