Hey,
I built a pc a month ago exactly, and for the most part it's been working fine.
Usually when I turn it on I have to HOLD down the power switch to restart it (it RARELY works first time for some reason, it STICKS when loading XP) but apart from that I haven't had any problems; it's all worked perfectly since I put it together.
Last night I shut down my pc after playing games for a few hours but when it turned off it turned itself on again instantly. Being relatively impatient I hit the switch on my PSU to kill it.
That's the only out-of-the-ordinary thing that happened (and even it's happened a couple of times) but now it won't boot.
I keep getting continous, long beeps and nothing at all happens. Apparently this means there's a memory problem but I don't see how that can be the case; the machine has been running fine for a month and I've not done anything. Even so, I've taken both RAM sticks out and swapped them around (a suggestion from friends) and it's still doing it. I've CHECKED for loose cables etc and everything LOOKS good to me. It should also be noted that it's still starting itself. As soon as it gets power from the wall socket it turns on, without me hitting its own power switch.
Any help would be greatly appreciated - Oblivion comes out on Friday

Specs:

AMD Athlon 64 3800+ Socket 939 512KB
MSI K8N NEO 4 PLATINUM S939 nForce4 Ultra ATX A L R
Corsair Memory TWINX2048 - 3200C2PT XMS3200 2x1GB 2x184DIMM CAS2
Try the system with one stick of RAM in only (it's unlikely that they have both failed) and with all unnecessary cards removed (i.e. everything except graphics card). What happens?It works. I don't believe it.
Surely that chip can't be broken already?

Wow, it's even started XP first time. That never happens.
Do you think I should take this chip out and try it with the other one on its own and see what happens?Yes, definitely. Also try turning on ECC checking in your BIOS (if you can find that option).Okay, I replaced the working chip with the other one and it died again.
I guess that chip must be faulty somehow.
I haven't checked out the BIOS yet but I will.
Thanks a lot for the help.A pleasure. Feel free to come back with any other problems.