at first, about a week ago, it would freeze randomly (just freeze up, no bsod or anything) and emit a single high pitched beep from the speakers (not the internal speaker) that would play indefinitely until i hit reset. that happened a couple times a day for a little while, sometimes it would be fine for a couple days straight. it usually happened when i wasn't at the computer, just playing mp3s with winamp and maybe had utorrent running and not much else. then it started freezing, without the beeping, more and more often - within the span of one evening, to where eventually it was freezing as soon as it booted up, or even IN the bios. also half the time i hit reset and it won't post, i'll then hit reset several times in a row and it will post, but will freeze before it finishes booting up. it seemed like a heat issue but in the bios it says i'm running at 50 degrees C. (not exactly cool, but not overheating temp either). i took apart and cleaned the (stock) heatsink and fan just to be sure. i then took the cpu/heatsink and memory out and put them into a different machine, i booted from a memtest cd and ran the tests for about 19 hours with no errors. my next guess was the power supply - a thermaltake 430watt unit that i've used in a ton of builds and never had a problem with ever (the one with like, 1500 positive reviews on newegg.com). so i replaced it with a thermaltake 500watt pure power. i then booted it up and everything seemed fine! for five or ten minutes, then it froze again and is now back to where it was yesterday. this makes me again think it's some sort of heat issue, as it worked for five minutes or so but it was off for a couple hours before that. any ideas? all i can think of next is replace the video card? it's an msi nvidia geforce something.. like 7800 or so, i'm not sure exactly. thanks in advance!

Have you ran Memtest86 to check the physical memory ?

as i said in my post i ran it on another machine with the cpu and memory from this machine in it. i'm now running it on this one, but i fear it will freeze during the testing - maybe not, but since it was freezing in the BIOS i assume the chance of it freezing during the memtest is just as great.. ?

okay so i just booted it from the memtest disc and yep, it froze after 9 minutes of testing.. though one thing i noticed, the cursor and the asterisk on the screen where still blinking, so the whole screen didn't freeze.. but the rest of it did, so that maybe rules out the video card? i'm stumped...

double check all the simple things first like cables broken wires etc make sure that the system panel connectors are not broken and the usb connections are you saying that it is not making post? or is freezing when in the gui?

okay i'm REALLY stumped now.. all the basic connections and things were fine. the computer hadn't been moved or bumped or anything and has been working great for the past year or more and then this freezing problem came on pretty suddenly. SO.. i've swapped out/tested the memory, cpu, power supply, and video card. all to no avail. so i thought it must the motherboard. it is a cheap (tul) one after all. so i was about to swap out that, but before i did, as one final test. i took the mobo out of the case and attached just the power supply, video card, memory, cpu, and cd rom, and monitor, and booted it up off the memtest cd. so far it's been running for 20+ minutes with no freezing (before i couldn't get past about 9 minutes before a freeze in the memtest). so i don't think it's the motherboard. all that leaves as the cause of the constant freezing is either a hard drive (there are five of them - but they all S.M.A.R.T. test okay on bootup) or an optical drive, or another device (i have a USB card reader, a usb mouse and keyboard, a firewire audio recording device, and a pci sound card) - or it's a software issue. which i highly doubted as it was freezing in the bios and not posting half the time, which i guess is maybe possible with some viruses? but i've never really had a problem with virusus. i run norton systemworks and hijack this regularly. only browse with opera and stay away from any kind of spyware crap. and i have booted it up with most, if not all, of the peripheral devices disconnected. so really, if it's not the motherboard, at this point, it seems like it'd have to be one of the five hard drives or one of the 2 optical drives. though i've never heard of a hard drive causing a ton of random crashes, i guess it is possible... help, anyone?