I gave installing a brand new EVGA GeForce GTX 480 in my system tonight. Things didn't go so well... got everything hooked up and ready to go, hit the power button and the machine started booting for approximately 3 seconds, then cut off, then powered on again.
I double checked all my wiring to make sure I didn't plug in anything incorrectly, and it looks good. Decided to just take the video card out and boot like that... same symptoms. Uh oh.
Gradually disconnected everything from power save for just the mobo/cpu/ram... same behavior. What could I have messed up?
Thanks in advance - I can provide additional details as you folks deem relevent.
Try clearing your cmos, see your owners manual, and see if it will boot up again.
Also please list your system or if its a pre-built then let us know the make and whole model number. For example: acer aspire would not be very helpful whereas acer aspire 5532 would allow us to find exactly whats inside.