I think I saw your post about the motherboard, but dismissed it as I started writing my reply. It happens.
Sorry to hear that you've gotten no love from the testing. There are a few things to do from here.
Swap out your power supply. It's the fastest & easiest way to make sure there's not a power issue going on. Get a spare if you can, buying a new one at this point is a bit premature.
If the power issue is fine (i.e. same results on a different power supply) it's highly suspect that it's the motherboard at this point, which means you'd have to buy a new motherboard.
At that point you have to consider if it's worth troubleshooting the system to pieces, or just take your new video card, call it even and buy or build a new system.
Entirely up to you and how much you want to troubleshoot it.
Sorry to hear that you've gotten no love from the testing. There are a few things to do from here.
Swap out your power supply. It's the fastest & easiest way to make sure there's not a power issue going on. Get a spare if you can, buying a new one at this point is a bit premature.
If the power issue is fine (i.e. same results on a different power supply) it's highly suspect that it's the motherboard at this point, which means you'd have to buy a new motherboard.
At that point you have to consider if it's worth troubleshooting the system to pieces, or just take your new video card, call it even and buy or build a new system.
Entirely up to you and how much you want to troubleshoot it.