Originally Posted by Onions
take your ram out and oly put one in to eliminate that problem.. put your 260 in (its confirmed working) and try it.. if its still dead rma the mb if you an as thats prob the problem...
Use only one, try in one slot. No go, then try same stick in different slot. No go, try another stick (still using only one stick) in first slot. No go, try in other slot. This will eliminate ram or ram slots, both of which would cause this problem.
Next up is psu. Grab another and use it in your rig (as apposed to using that one in another rig) no go, move on.
Still unclear on if you've reset bios yet. Use the jumper or the battery, but jumper's easier. I've never heard of turning the computer on with the jumper moved over. That could be dangerous but not sure. Either way, no need. Move it, wait a sec, move it back. Turn it on, no go...
Remove every other component, power on with only psu, motherboard/ram/cpu,only one stick of ram btw, and if you load bios start plugging things back in one at a time. If not...
And you've tried your origial video card that was working before?
Then I'd say narrowed down to cpu or motherboard, with a 98% chance of motherboard.