Fried my motherboard?

So, I recently bought a new CPU (well, a used one) for my rig, an Intel Q6600.

My rig is:

Intel Core 2 Quad Q6600 (was Intel Pentium Dual Core E2180)
Gigabyte GA-N650SLI-DS4L (nForce 650i SLI chipset)
2 * 1GB DDR2-800 memory (OCZ brand, good memory)
2 * Palit GeForce 8800GTX, SLI
3 HDs, 1 DVD
Antec P150 case

So, I replaced the CPU, and finally got everything working. Was fine, stable, and I was happy. But then I had to fudge with the Overclocking controls of the mobo, and I did the following:

CPU voltage control: 1.35v
NB/HT-link voltage: +0.1v
FSB: +0.1v
FSB-Memory clock mode: Unlinked
CPU host frequency: 333mhz
Memory frequency: 800mhz

And from that point on - black screen. No beeps, nothing. CMOS clearning didn't help. Replacing a battery - didn't help. Disconnected the video, the HDs/DVDs, took out the CPU and memory - still no beeps. So - just the motherboard is connected now, with just the case pins and the PSU, nothing more. No beeps.

I highly doubt it has to do with the PSU, but I can check it with another PSU, just in case.

I was wondering - do you have any suggestion as to what I can do? What can it be? Any help would be appreciated, as I am truly clueless as to what to do next.