Basically my HTPC went down couple of days ago. Specs: Intel E6400 Core 2 Duo DQ45EK motherboard 4GB RAM 275W allied Power supply. There is standby power going to the motherboard. But the PC refuses to power up. All I heard is a click in the PSU. Fan doesn't spin. Removed 2x2 AUX power, fan spins up but nothing appear on monitor. No beeps either. Swap over to an old motherboard (this motherboard had power up issues before, so not a good test). Doesn't uses 2x2 power but uses molex power. Fan spin up, but no boot codes.
Found the problem ... It's definitely the motherboard issue.. I swap over the PSU from my main machine. I just realized it has the 2x2 AUX power connector.
Not to point out the obvious, but can you check if the motherboard is shorting somewhere? Maybe a screw got lodged under it? My system refused to power up like this last time, and it was all because of a screw lodged under the motherboard.
I even took out the whole motherboard and place it on the carpet I have to use back my old full ATX evga 680i motherboard. I don't have a case for it The current HTPC case only fits up to mATX.
Errr.. carpet?? Static damage, dude! It's cold over there right now, right? If you have the anti-static bag the motherboard came with, you can lay it between the motherboard and the carpet / floor. Is the PSU old or new? It didn't work with the PSU from your main machine, right? I would check to see if the copper clips inside the connectors are okay. Maybe use a pincer to squeeze them a little if they are too spread out.
That's a good reminder about static electricity. Has been hella cold and dry over here last few months.
Yeah. Static is cold weather sucks. But luckily I don't get static from my carpet. The PSU from my desktop is older, but works fine with my ivy bridge quad core. Doesn't work with the broken Intel board. I swapped the CPU and RAM to my old evga 680i board, it works fine with the other PSU.
I think there's really such a thing as PSU incompatibility issue. I have to buy a new PSU because my old one wasn't compatible...