The ASRock x58 Extreme is a good board, similar to the ECS x58B-A. You're not going to get higher than a 3.6GHz overclock, but for $170 and a board that supports at least 2 PCI Express 2.0 x16 for SLI or Crossfire (abswindows7 doesn't know what he's talking about), you're getting a great deal.
A lot of things can go wrong, but I take it that you're new to overclocking. It's quite possible you:
1. Used stock thermal compound and heatsink causing your temps to skyrocket while leaving your computer running Prime95 overnight without monitoring your temperatures first. In that case, you probably fried your CPU.
2. You used adequate cooling, and not stock thermal compound or a stock heatsink, but you didn't attack the heatsink properly. Same thing as #1, you didn't monitor your temps and let it run overnight.
There's no need to run Prime95 longer than 10 minutes. If there's no errors in 10 minutes, it's not likely you'll get errors in 8 hours. All you're doing is wasting the life of your CPU. For the i7 920, overclocked to 3.6GHz, there won't be any application you'll be running that will put a full load on your CPU for even 10 minutes.