At this point you need to try and isolate the problematic component, not easy, but perhaps you can have a Computer Store (local ma n pop) outfit help you out by supplying additional parts.
- Try another monitor but very doubtful its the monitor (Have you tried both DVI outputs on the 285?)
- Try GPU in another Rig......(highly unlikely the problem as you've tried it now with different GPUs)
- Try another PSU (I've had to RMA a brand new Corsair PSU) - this is what I would suspet, either the PSU or the Mobo.....PSU test is easy, just get one from ma n pop and give it a whirl...
The above 3 troubleshoots are easy enough...just need the "ma n pa shop" to help you out a bit....the Mobo swap is the last straw, but in the event the other 3 items above are fine, this is likely the culprit.
Once you can determine that it isn't any of the above...then move onto the Mobo......it sucks, but its the way it is....this is why I never sold my 2nd Rig, its always handy having "spare working parts" kicking around.
Forgot mention: If your CPU is OC'd, go back into BIOS Reset everything to default, reboot, then shutdown the Rig and reset CMOS, give that a whirl 1st before tearing apart, also ensure your running the latest n greatest BIOS version, you just may get lucky
