I just installed an Asus P6T mobo, in an Antec 1200, with an i7 930, and I am having problems with the system panel connector (power sw, you know, the thing with the power/ground and reset/ground that plugs into the case power/reset wires). If the case sits for a long length of time, it won't power up. I hit the power button and it doesn't do anything. It's been doing this since the first power up after installation. To fix the problem, although temporarily, I have to pull the system panel connector adapter out, replug the reset wire, the power wire and the led wire, and plug the adapter back in. Once I unplug it and refit all the wires, it boots right up.
It doesn't happen in short intervals, however. I can shut the system down, wait a few seconds, and it'll power right back up.
Finally, after I refit all the plugs on the system panel connector I have to change the boot order on my hard drives. Don't know if this is related though...
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