Well, my second board was working perfectly, until I tried changing my RAM timings.
I had finally gotten a better heatsink than the A64 stock(I'm now using an opteron stock heatpipe unit). I had gotten my CPU overclocked to 2.4(w/ 9x multiplier, at 265 HTT), but I couldn't get my ram to run stable with the 166 divider(about 220 mhz), so I tried to reduce the timings on my ram(changed from 2.5-4-4-8 to 3.0-4-4-9), and the motherboard would not finish POST at all after that change. It would get as far as showing me my RAM amount(2048MB), but would not go past that.
I tried to clear the cmos, using the clear cmos jumper. After clearing it, the board POSTs, but it only detects 16MB of ram, it says the cmos battery is low, it says the cmos date/clock is wrong, and it says to press f2 to enter setup or press f1 to load defaults and continue. After the POST screen, it clears the screen and displays an error message at the top: Please choose the correct boot device, or insert boot media into the boot device and press any key.
I can press a key all I want, and it doesn't boot(or even seem to respond), ctrl-alt-delete does nothing. I cannot get into setup by pressing F2, and I cannot get it to load defaults and continue by pressing f1. I've tried both a USB and a PS2 keyboard. I even tried disconnecting power and pulling the cmos battery for 30 minutes. I got the same message after I had hooked everything back up.
Anyone have any ideas? I'm at work now, when I get home I'll stick my ram into another system just to make sure it works(I really doubt thats the problem), and I'll pull the battery until I hear from ASRock or someone with a good idea. I really want my system back. It was prime95 stable at 2.4, at 45C, so I don't think I've cooked my CPU. I don't see how I could cook my ram by setting timings slower than stock? And shouldn't that be completely cleaned up after a bios reset? I'm a bit annoyed, since I am currently without my desktop completely, until I get this resolved.
At this point, the only things connected to the motherboard are: CPU, CD-ROM, Floppy, 4 sticks of ram, video card, sound card, ps2 keyboard, usb mouse. I don't want my hard drives getting a ton of power cycles as I get this worked out, so they're completely disconnected from power and SATA. I disconnected all my USB devices except the mouse. I've tried removing my ram two sticks at a time, so that I only have two sticks in - still only detects 16MB, still gives the same error.
Edit: Tested my ram, it's fine.
Called ASRock. Do they only have one support guy?

Anyways, the board is being RMA'd. Heres hoping #3 comes out ok.