I decided to upgrade my ageing Radeon X1600 and grab a HD6770, but after installing it the computer boots up, waits a few seconds then powers off for a few (usually powers on for around 3 seconds or so but it can vary!) It then powers on again and the cycle repeats. I get no output from the card in the short time it stays on.
Any ideas? Originally I thought the power supply was likely not beefy enough, but after trying two others that are more than powerful enough I get the exact same symptoms, so I'm pretty sure it's not that. Equally I wondered whether the card was dead, but in a friend's system it works fine.
I'm left with the motherboard, a G41M-LE - but it's running the latest BIOS and I'm not sure what settings I could change in the BIOS to fix it! (Restoring the default settings didn't work.) It may well be running an older version of PCI-E but I thought they were meant to be backwards compatible?