I have a new computer that is giving me some troubles. Or more specifically, the new graphics card is the culprit.
Motherboard: Asus M4A785T-M/CSM
Memory: 4g DDR3 (4x1 g)
System Windows 7 64-bit Pro edition
Video card: DIAMOND 5770PE51GXOC HD5770
After installing Windows, the computer works correctly with the monitor running from the on-board video card. Everything checks out so far.
The graphics card did NOT include a 4-pin to 6-pin connector. My power supply (new and rated at 585w) did not have a 6 pin connector. After reading some of the posts here, I purchased a 4-pin to 6-pin adapter which is plugged into the card and the power supply.
When the adapter is plugged into the video card and the new video-card is put into the computer, the computer does not get past POST. Unplugging the power from the video card allows the computer to be rebooted using the Onboard video card.
I have not gotten so far as to even try to disable the onboard card (as I am supposed to do once it is installed) as the computer cannot seem to see the new card.
I was concerned about that. The PSU did not have any 6-pin connectors but the card's instructions suggested that a 4 to 6 pin connector would suffice. I am at work at the moment and don't recall the exact name of the power supply. Judging from the bill of laiding, I *think* it is an Orion XPOWER585 585W
Coming back to this... the connector was defective. Got a new one and the card came online perfectly. Didn't even have to go through the 'disable onboard video card' rigamaole - Windows 7 handled it beautifully.