[Edit: turns out I had to update my bios -- I bought the mobo the week LGA 1156 came out, so using the 2008 it with an i3-540 was a bit sketchy]
I re-built a system from parts I had lying around:
Intel Core i3-540
Antec Sonata III
500 W Antec Green power supply
4 GB of RAM
Caviar Black 1 TB
Corsair A-50 air cooler.
Zotac GTS 250
And it works fine, except.. If I put to to sleep (Windows 7, Start -> Stop -> Sleep), it won't come back up.. Well, it sort of will, but nothing comes on screen.. the reset and power switch on the front of the case will become non-responsive (I checked that they are plugged in the proper pins on the motherboard), and using the mouse/keyboard won't do anything. When in this state, the front Power LED will be on, and the DVD-RW will open if I push on it, and the fans will be running. The only way to bring the computer "back" is to switch the power supply on and off at the back of the case.
I've looked in the BIOS to see if there was a setting I had messed up, but nothing seems to be linked to sleep per se... For the time being, I've just made windows not go to sleep, but this is not optimal. Any idea what is up?
i5-750 @ 3.3 GHz; Asus P7P55D-E Pro; Thermalright Silver Arrow; Antec P183; 4 GB; 2x Radeon HD 6950; Corsair HX650.