Gigabyte GA-EP45-DS3L boot problem

Hello,

The 1 long 1 short beeps relates to the video card. Just double check the beep codes. Sometimes as a fan spins up, it's hard to separate out the short beeps. Try booting with no video cards in place. See if you get exactly the same beep codes.

Obvious question, did you upgrade the video card drivers recently, or possibly thru Windows 64 Update? A bad low level video driver could be the culprit. That might prevent either 4870 from initializing. Using the NVidia card would use different default drivers which could boot fine. If any questioin, you can uninstall the ATI drivers, and see if it will POST using the Win-7 default drivers, then reinstall.

The other possibility is that 1 or the two 4870's has died. Try to boot with only 1 4870 in place, then try the other, to see if one of them will permit normal POSTing. (with a bad driver, neither would POST)

A PSU that is not delivering adequate power at startup might prevent video card initialization - you tried a separate PSU with no change, which is good troubleshoting.

Those steps should help you pin down the problem

Actually, 1 long and 2 short suggest a problem with your RAM. Try removing/reseating your RAM, one module at a time. Also, when you get your display back, run MemTest86+ . Download the latest version of the .iso (disc image). Burn said disc image to cd. Pop disc into troubled computer and let the test run.

Any errors found suggest failure in RAM. Allow the test to run through several passes (about 8-10 should suffice).