I had a 320 GB hard drive I was going to use from an old build I had awhile back from a computer about 2~ years ago since has been out dated so I didn't even bother upgrading it just went from scratch aside from the hard drive. I had built a similar computer for a friend of mine about 4 months ago all went fine new hard drive though motherboard and GPU changed a bit for personal preference.
ANYWAY on to my problem I started up fine the first time mind you this computer vista 32 bit and I was planning to use a windows 7 upgrade 64 bit obviously to get away from that OS and upgrade to 64 bit; before I even got to the account selection screen the computer crashed and when I power on it only powers on for about 2-4 seconds fans etc then shuts off. I have yet to get past that I rechecked my plugs made sure I had all of my stuff wired correctly took out the GPU to see if it was that, switched RAM slots. After that I decided maybe it was a CPU problem or maybe the connectors to the CPU on the mobo were bent anything really at this point. I connected it back up but in the process I forgot to put the power back into the hard drive so I couldn't boot off that and when that happened I had the screen that said "Cannot boot from disk insert blah blah and press enter".
With that said what do you guys think it is I have a pretty good idea that it had something to do with the fact that I did not uninstall my old motherboard drivers/GPU it slipped my mind I should have clean installed. Do you think I killed the hard drive or would a hard drive even prevent a computer from powering up to at all aside from the 2 seconds initial fans turning on. Let me know what you guys think the problem is I have an SSD coming in on Saturday I will try to clean install on that I currently have no extra Hard drives to test this theory.