Secondary hard drive (sometimes) doesn't appear

Vi Monks

So here's my problem. Sometimes, maybe once a week, I start up my computer, and my secondary hard drive isn't there. Can't see it in explorer, shortcuts to it don't work. Restarting or shutting down fixes it, though sometimes it takes a couple of attempts.

I have reason to suspect it might be my mobo (but I'm not quite tech savvy enough to be sure). I recently bought an HD 5850. Turns out, it doesn't play well with my particular model of mobo. If I do a cold boot of my pc, the mobo doesn't recognize that there's a video card connected (confirmed the beep codes). In order to get my computer to start up from a cold boot, I have to hit the power button and then hit the reset button a few seconds later.

What makes me suspect my mobo is this: sometimes that process doesn't work. Maybe once or twice a month, I'll go through that process and the mobo still won't recognize the video card. Normally takes 5-10 minutes of restarting to get it to see the video card.

Any ideas? I'm stumped.

Edit: I've found that the hard drive also does not appear on my BIOS POST screen, so I know it's not a Windows problem.

skybox

What brand of motherboard? The video card issue sounds very similar to one I had, though it didn't sometimes take 15 minutes to get around. I never found a complete solution to it, though. Beyond never buying that brand again, anyway.