After BSOD and memory tweaks, no POST

Several months ago my power supply failed (terrifyingly--smoke and everything). I finally got around to RMAing it, and yesterday I reinstalled it. Everything seemed fine for a while, but today he machine BSODed out of nowhere. (Didn't catch the specifics of what it said). Well, the BIOS settings had been cleared when I installed the new PSU, so I figured it could be a voltage issue. Went in and changed to 2.1v, which had been the previous setting. Boot proceeded as usual, but then froze as I was typing in my Windows password. I did a hard shutdown, and since then it hasn't posted. All fans spin up, but nothing on the monitor. Unfortunately my motherboard (P5Q Pro) doesn't have any diagnostics except speaker beeps, and I don't own a speaker. I've cleared the CMOS and tried taking one RAM module out at a time, and switching DIMM slots, to no effect. I also reseated the video card power cables. Don't own other suitable memory or video cards to try. Does it sound like I fried my RAM, or something more sinister?

OS: Vista
RAM: GSkill, 2x2GB
GPU: Radeon HD 4870
Mobo: P5Q Pro
PSU: Antec TruePower 650

Got the speaker. No beeps. The manual seems unclear on whether or not that's the default--it says "One beep means VGA detected, Quick Boot disabled, no keyboard detected," but doesn't mention no beep at all. So at first glance the mobo seems suspect. But then I took out both sticks of RAM, and it correctly gave the code for no RAM detected. Thoughts?

Another note: two red LEDs quickly flash on the video card upon powering on. I haven't turned the machine on with the case open often enough to remember whether that's normal...any 4870 owners know about that?

Huh, strange. I couldn't figure out how to remove the battery, so I decided to put one stick of RAM back in in the meantime to see what the speaker said the second time around. The thing posted! So I figured maybe the other stick was dead, but when I swapped that one in it posted again. Well, maybe it's the DIMM slot--nope, with both sticks in it posts as well. Very strange. I'm running with auto RAM voltage and auto timings, and crossing my fingers for no bsod. Still no idea what caused the first one, or why it decided to wait two days before booting up correctly. Hopefully I'll never have to get to the bottom of it...