Whenever I have an issue with one of my computers, I can usually sort it out myself with a half-hour of persistence and the knowhow of someone who grew up breaking Windows 95 and assembled his first computer from parts at 12 years old. When it's a really specific problem that most users won't encounter, Google usually leads me to an answer, and over the last few years most of my problems have been solved by reading posts on Tom's Hardware. The people around here even tend to use intelligible English (which always a bonus), so I choose you to approach with my conundrum.
To get it out of the way, the parts stuck in my metal box are as follows:
Intel Core 2 Duo 8400 (3.0 Ghz)
Nvidia Geforce 9800GTX+
Asus P5N-D Motherboard (because at the time of upgrade I was still using some IDE
4x1Gig Ballistix DDR2 at 800Mhz
Ocz 700W PSU
Western Digital 500 gig SATA HD
Some other junk (40 gig IDE HD, generic IDE DVDRW, floppy drive)
Running Windows XP Home
The confounding part of my issue is that none of the symptoms are constant, or (from my knowledge, anyway) seem to be coming from the same parts. I probably can't remember all the symptoms I've had because there have been so many and such a wide variety, but I'll give some examples. Keep in mind when I say "runs flawlessly" I mean nothing out of the ordinary going wrong while often pushing the limits of my system with high end games cranked all the way up or near-neurotic multitasking.
1. After running flawlessly for a month or two I started having IRQL crashes. None of the numbers given by Windows should have caused any conflicts, yet they kept happening. Even on a fresh install of Windows, I was getting IRQL errors, and even after disconnecting all unessential parts of the computer. Even swapped out hard drives with a fresh install of Windows, no luck. About three days later the problem stopped on its own.
2. Flawless performance for another considerable length of time, followed by RAM errors. I can't remember the exact codes, but the problems where Windows crashes when it tries to access an address that has been cleared, and the problem when a crash is caused by attempting to clear an address that has already been cleared. I could not find a reason for this. I ran all my hardware as hard as I could with multiple programs like Orpheus (and some programs specifically designed to test each and every bit of RAM, read/write, with varying algorithms) and some games like Crysis Warhead turned up to 11. Crashes continued, with no apparent cause, as all hardware tested as healthy as I'd expect of new parts. Switched RAM into another computer, worked fine... switched another computer's RAM into the faulty combine, secondary set of RAM worked fine. Put my old RAM back into the faulty combine, problems stopped on their own after about a week.
*** As I did a lot of hardware switching to narrow down the culprit, I'll just call my 1300 buck scrap heap "The Faulty Combine" for now.
3. After more flawless performance, my 500 gig SATA started to have CRC errors (Something I've only seen happen with a hard drive when you're trying to write duplicate filenames into folders that cause naming problems, such as trying to save a file as "003.jpg" to "D:/Folder A/Folder A/003.jpg" when "D:/Folder A/003.jpg" already exists). Sometimes games would crash because of failure to read files off my HD, sometimes it'd fail to write files, sometimes the scrap heap wouldn't even acknowledge the drive existed. This happened with both the SATA and IDE. Switching hard drives from another computer into the Faulty Combine replicated errors. Given a fair amount of time after I had given up on fixing the problem (I think in this case it was two weeks) the errors stopped on their own.
4. Without any other warning signs of hardware failure, booting lead only to "NTLDR not found". Looked, NTLDR and ntcom were right where they were supposed to be. Reformatting, reinstalling, nothing fixed it. Found out through trial and error booting only succeeded when the XP installation disc was in my optical drive. File versions were correct (though that shouldn't matter on a fresh install anyway). This continued for about a month until my computer "decided" to go back to flawless operation. Booted with no disc just fine.
5. Somehow during another period of flawlessness my BIOS took a header off a cliff, and landed on the pitchfork's handle instead of the hay. I flashed my BIOS and found out the next time tried to boot that it had died again. I've heard flashing your BIOS constantly isn't a good idea for one reason or another, but my computer wouldn't boot unless every time I restarted I flashed the BIOS. Friend of mine sent me an motherboard (think it was Gigabyte, don't think it matters much due to the circumstances) and his old video card (a Radeon something or other, used in testing later). I swapped out motherboards, problem went away for a while. Bought a new P5N-D figuring the motherboard had to be the issue (all random parts having trouble, all random parts go through the motherboard, motherboard is the problem, yeah? Uh huh... I wish.) New P5N-D worked fine for a good few months, then *6. At *6, tried friend's motherboard in the Faulty Combine, that didn't fix the issues.
6. Started having failures loading textures in games. Textures were replaced with blackness, white lines, letters and words, random shapes, random colors, etc... games looked like the inside of Turok II's Mantid Hive while mixing acid, shrooms, and mescaline and "Dude, totally havin' a bad trip, man." FPS suffered greatly, no observable ill effects from other computer parts or software functions. Windows ran fine, video files worked fine, games were a nightmare. Replaced 9800GTx+ with my friend's Radeon, problem disappeared. Out of frustration (not knowing what is causing this is extremely frustrating) I put my 9800GTX+ back in the Faulty Combine and saw no further graphics issues.
7. After another couple months of flawless performance (up until about a week ago), I was playing The Last Remnant and the game's 2 second loading screens started taking 2-3 minutes, graphics were skipping, and finally upon restarting my computer the game wouldn't even load. Task Manager said the splash screen would load about 300megs into memory and then stop. After some more poking around, I found I couldn't use Task Manager to end processes reliably anymore. I waited a day or so hoping it'd get better, but soon after even stuff as simple as playing a video file was skippy, and then even Firefox wouldn't load. I tried wiping the hard drive as usual (since for no apparent reason fresh installs and a few day's time afterwards have fixed *some* of my problems). Couldn't get Windows to boot from install disc for a while, then finally got it installed. Reinstalled the latest chipset drivers, HD Audio drivers, tried to install display drivers with no luck. The error message I received said something about visual runtime errors (the words that come to mind are Visual Runtime 2005++ or Visual Runtime C++ 2005, something similar). I've never had a problem installing display drivers, even if it's the first thing I do after a fresh install, so it's not because I forgot something the InstallShield needs to run. Windows also said its display drivers had been replaced by ones it didn't recognize and wanted to replace them with copies from the XP install disc (I'd never seen that message before either).
Currently getting Windows to boot requires 5-6 restarts (and then it's a maybe, assuming one of the loading screens doesn't hangup forever) and when Windows does finally boot, I can only click Start, open My Computer, right click desktop, or other really simple tasks until the computer freezes up entirely except Task Manager. Pushing a few buttons freezes Task Manager, requiring a restart of the entire process all over again. I'm not even able to install any drivers anymore (and since I tried another last stand HD wipe my ethernet drivers aren't even be installed... not that Firefox would load anyway).
I've had many other similar problems, most rendering the computer unusable, all appearing with no warning and disappearing through no action of my own. I'm at a complete loss here. If it's a faulty CPU, why the random problems? Why do they go away for no apparent reason? If it's faulty wiring and not one of the parts in particular, why does it effect EVERY part now and then but never all at once? I'd think bad wiring would only be likely to happen in one spot at a time and cause complete, permanent failure of the device until the wiring's replaced (not "heal itself given time and threatening comments"). If it's the motherboard, why does a new motherboard not fix the problems (if it's not wiring either)? If it's the power supply... I don't even know, wouldn't the whole thing have fried two years ago when I first started having problems? While I understand that "just because it's always *been* doesn't mean it always *will* be", I've never encountered anyone having PSU problems, ever, and it seems even more unlikely with a decent one like an Ocz.
I was considering upgrading my CPU to the 3.6ghz version to see if that fixes the
problem (as the only things I haven't replaced/swapped out/etc are the CPU, PSU, and the wiring), but I don't want to risk putting a curse or hex or bewitching on a perfectly good processor if the CPU isn't the problem. At this point I'm considering testing the power supply with some borrowed equipment to make sure it's good, and using the PSU and video card while moving on to a new motherboard (which'll replace the wiring), hard drive, DDR3 and getting a core I3 or something similar. I tend to think I have the patience of someone awaiting the Second Coming, but after two years of issues that don't even make sense to me, I'm tired of this rubbish.
Help me, Obi-Tom's Hardware; you're my only hope.
First thing that comes to my mind is a faulty PSU, or inconsistent voltage on your AC power line, which could also lead to a faulty PSU. I had this type of problems, from RAM errors to HDD errors. They were all because of my PSU. Also sometimes the problem come from the motherboard. So if I were you I would try another PSU for a few weeks, and see how it goes.