Ok, I read the FAQ, and disconnected everything but the HDD and CPU but am still having problems. I could pull the mobo back out, but I counted screws out and screws in, so likelihood of screw underneath slim.
I have a Gigabyte AM2/AM3 mobo with a AMD Phenom II X4 CPU and Coolermaster Gemini II fan/heatsink. I've got a brand new (blank) 500GB Seagate HDD and a Coolermaster 700W PSU.
I finally got it all put together, and when I pushed the power button, lights blinked on, CPU fan spun, and HDD woke up--- but only for a split second, and then all went dark.
Pushing the power button again does nothing.
HOWEVER- If I shut off the PSU with the switch on the back, wait 1/2 a minute, and THEN push the power button, the same thing happens (everything lives for a split second then dies).
Bonus info: I'm using an *old* compaq case that I had to mod pretty heavily to get to work- including soldering longer wires to the power button. Also, the power button is the kind that is always "springy" meaning that it doesn't have a noticeable "On" versus "Off" position. Finally, when I spliced the wires from the power button to the connectors, my splice was 24 gauge doorbell wire instead of the 22 gauge wire that was used.
ok, i pulled mobo just to double check- no screws underneath. only thing conceivable is the cooler mount has a metal bracket that attaches underneath mobo, but it has insulated feet... is it possible that the OEM standoffs aren't tall enough for the gigabyte mobo plus cooler?
Breadbox it to make sure its not a short with the case.
You plugged both motherboard power cables in?
Any chance you have a friend with a PSU you can borrow to make sure your PSU isnt bad?
Ok, I pulled my mobo out and put it on a nylon cutting board. Only CPU, Heatsink/Fan, and PSU are connected.
Used screwdriver to short power pins (thank god my wife isn't home- if she saw me using her cutting board to hold electronics while jamming a screwdriver into them she would freak the F*ck out!) and same issue.
Used a multimeter to test plugs on PSU. I tested from Common to the 12VDC pin and it reat 23millivolts (DC) if I'm using this thing right. So, bad PSU?