I have this problem with a system I built myself and cannot figure out what is going on (sorry if this is in the wrong forum). This problem happens (seemingly) randomly. If I am playing WoW and watching a video (i.e. hulu/netflix) simultaneously, sometimes my computer will freeze. First my display will go black--i.e. no signal to monitor. Then my computer will do something even weirder. It will give me 5 beeps and then lock up. Sometimes this will happen if I'm just playing Skyrim after awhile, but not always. Obviously this happens while I put stress on the comp but I cannot seem to pin down the issue.
The only way to restart the computer is to do a hard restart. I have no idea what the problem could be. This has been happening for a couple of months now, but I really want to get to the bottom of it. I'm currently doing a stress test (few hours so far without any problems) -- Prime95. I also did a FurMark stress test for my GPU without any problems. Any ideas? PSU maybe? Haven't done a RAM test yet. My temps seem a little high but fine: CPU below 60c, Core 1&2 below 77c (taken with speedfan while doing this current Prime95 stress test).
Check the beep mode and if can asking help (email) to the motherboard manufacturer to consult for possible solution. Did you try to reinstall windows and test on it? It might be hardware problems but also could be software problem and you need to solve it one by one. If you think that your hardware are all good, give it a try to reinstall the OS!