[delta_7890]

So I got a new computer not even a week ago, and it's developed a very annoying problem.

The length of time varies (though it usually takes several hours) until this dreaded event occurs.  The monitor goes totally blank (and into its Power Saving Mode), and refuses to return the display.  The sound cuts out a few seconds afterwards, leading me to believe that the whole computer just goes kaput.  However, the tower does not turn off.  Turning it off manually and turning it back on...brings the computer back online, with no telling on when it will happen again.  It's not particularly crippling, but it is VERY annoying.  It shouldn't be an overheating problem (of course that's always a possibility).  It is not a problem with the current graphics card, as I had the old, ****ty on-board card replaced, and it did that before the replacement as well.  The power supply was also given an upgrade.

My current specs are as follows:

The tower itself is a Gateway GT5476E Desktop.
Windows Vista (32 bit I believe)
AMD Athlon 64 X2 Dual Core 5000+ Processor
NVidia 7800 GT graphics card
2048 MB DDR2 Dual-Channel RAM
320 GB SATA Drive

Not sure what else to list, but if I missed anything important, feel free to ask.  If anyone here has some good tips or even solutions, I'd be happy to hear them.  All of my drivers and system files are up to date.

[Scuddie]

What, if anything, are you doing when it happens?  Does it happen when you're idle, gaming, browsing, or does it even matter what you're doing?  Is air moving freely through the case?  Is the machine getting too much / not enough power?

Sorry to tell you this, but with the amount of information you gave, the problem you described can be anything at all, but is most likely heat or power related.

[Hippo]

Its overheating. I've had 2 computers do the exact same thing, and it was a heat issue with both.

[BloodEagle]

The only HP computers I've ever seen didn't have any vents on the front, sides, or top of the case. Horrible design, really.

[Grizzly]

Either a Power supply problem, or as the above people said, overheating.

Ask your local computer nerd for more details.

[delta_7890]

Well, the power supply was newly upgraded, so I don't think it's that.  And it happened before the upgrade as well.  Perhaps it is just overheating.

If that's the case, what should I do to resolve it?  The less expensive the solution, the better (though I don't want to skimp out on anything that will definitely solve the problem).

I also ran a memtest last night and confirmed that all the on-board RAM is fine.

I should also note that it seems to shut down more often when I'm gaming, though as I'm gaming most of the time, it's hard for me to tell just how much it turns off when running under normal operations.

[MI123645]

This happened to my old Acer.

After 20 minutes, my monitor would turn off. I thought it was just turning off to save power or maybe it had went into sleep mode, but I tried moving the mouse, pushing keys, nothing.

I was stumped. The only way to fix it was to manually restart it (I had no restart button, I had to hold the power button for 4 seconds to turn it off).

I checked the power settings and a long story short, it was the option called "Turn off the hard disks after this amount of minutes" that was causing the problem.

Vista has this too. You just need to make sure to change the time to 0 minutes on the "Turn off Hard disks" option.

If that doesn't work, then its probably overheating.

[BloodEagle]

If it turns out to be overheating, this is a simple solution.

---

On a side note, HOLY $@#$!

[Scuddie]

Take the side off the case and give it room to breathe.  Then go wild and play some games with maximum settings for a while, and encode a movie in the background or something.  If it happens again quickly, it would indicate poor heat dissipation for your northbridge or CPU. If it happens again and it takes a while (30+ minutes), it's not heat related.  If it doesnt happen again, it's insufficient air flow that's causing it.  I'd hate to sound like a pessimist, but considering it had the same behavior with and without the 7800GT (which should be the main heat producer in that system), and occurring with two different PSUs, I've got the idea that it may be a lemon board.  I hope you have a warranty on that thing.

[jr2]

Mmm.... when you upgraded your on-board GFX card... did you disable it in the BIOS?  IIRC, sometimes you must do that for the new card to function properly.  Also, most new cards like to have an "IRQ assigned to VGA port" in the BIOS settings.  Gateway GT5476E, hmm, ok, if I have time today or tomorrow I will look your computer up and see if I can find anything.  You have the latest drivers for everything?  Oh, yeah, and you can find more system specs using CPU-Z, see in my sig. 
Also, holding the Windows-key (between CTRL and ALT) down, pressing the Pause | Break key (above the Pg Up, Pg Dwn, and right-arrow keys), and then releasing the Windows-key will give you some info about your OS, I imagine it would inform you if you were 32 or 64-bit.

Oh, and @ Scuddie: Be careful about taking the side off.  In most cases, this is good advice, but some crappy computers don't have anywheres near enough fans going or good system design... I don't think any modern computer has this problem, but I know some older ones just relied on the PSU fan to cool the entire case full of equipment.  If you remove the side panel, the PSU fan just sucks outside air into itself, and the rest of the equipment must rely on radiant cooling (which is usually more than enough... but just so you are aware).  Most compys have a fan in front now, as well as the PSU fan.

[delta_7890]

Unusually enough, I think I solved the problem.  I went into MSconfig and disabled some of the start-up programs and useless Vista services.  It's been a day and a half now without a single crash, the longest it's ever gone.  I guess it must have been a software or driver conflict of some sort.  I'm...puzzled, but relieved.