This is my first post and I heard this is a good forum. My hardware is as follows:
8800 GTS 320MB (I think this is the problem)
ASUS P5Q Pro
Intel E8400
2GB Patriot memory (waiting for 4 from an RMA)
2x Seagate 7200.11 32MB HDDs
LG IDE DVD burner
Corsair 620HX PSU
Windows Vista Ultimate x64

Yesterday everything was working fine, I installed company of heroes opposing fronts. I attempted to patch it and the patch failed. I downloaded all of the patches from the THQ website and attempted to install them, they all failed. I decided to restart my computer, after it shut down it didn't boot up again. It didn't show the splash screen or the POST and I didn't hear any beeps.

I tried replacing the video card with another video card that I have at home, which had no effect. I out my 8800 back in and tried booting with the video cable in the other port. This time everything appeared, with a lot of artifacts. Everything ran okay in this condition until windows started to boot. It shows the loading bar pass a couple of times, then the screen turns black (even the artifacts disappear). Sometimes at this point it blue screens but it doesn't last long enough for me to read anything off of it.

When I reboot I boot into safe mode. This boots up fine, I can even launch Firefox and Messenger to get help. However, some web pages look okay while loading then just turn black when they finish, but I can still go back and look at other pages.

Also note, everything in my system is new except for the video card. I had an Ultra Xfinity PSU before and I think it was faulty and damaged my old motherboard. The reason that I didn't mention this earlier is because my video card has been working fine for about a week in the new setup. It just crapped out yesterday. I look forward to hearing your help

Did you connect to both MB power connections? You have two separate ones.

Did you connect the power to the 8800?

Did you update the BIOS to the latest?

How is your memory configured? If it's two sticks take one out.

Verify your memory settings are correct.

Are you using the stock cooler? are the push pins all seated correctly?

thanks for your reply, but
I did connect both mobo connectors
I did connect power to the 8800
I updated the BIOS about a day before it died
I only have one memory stick in, the other is pooched
Memory was configured manually and auto
No I am not using stock cooler, and it is seated properly

Any other ideas?

It's really hard to diagnose something like this remotely. That's why you have so few replies.

Based on your symptoms, I have a few guesses:

1. Motherboard failure. The only thing is, I don't know about artifacts... I thought those got created only on the GPU.... you are using 64-bit drivers everywhere, right?

2. RAM failure. This could be due to other factors such as wrong voltage or just RAM the board does not like.

3. You got a bad PSU. Your BIOS should have a few voltage readings, check those.

4. I think your BIOS has an EM64T switch somewhere, maybe check that is on.

Are you getting any Post Codes? Do connect the speaker just in case this helps.

If I were wearing your boots, I would get a really cheap video card - even a plain old PCI - and try to get a clean boot display. I would also try another monitor in case the monitor cable is flakky.

If I couldn't get a clean cold boot with a different "known good" video card, then I would be thinking motherboard. I would then clear BIOS to see if I could get that to give me a clean cold boot.

Sometimes it is best to pull everything out and bench it - just put something non-conductive under the MB, so the vid card is fully inserted (really important - the bracket is lower and could get pushed up). This forces you to unplug and replug everything which is why it works sometimes. Sometimes a loose screw drops.. Other times a loose connection is found (had one inside an Amphenol plug once)... Once I found a wire clipping in a PCI slot...

I ran memtest86+ before this problem and I got 4 passes and 0 fails. At the moment I am thinking that my old power supply damaged the video card, and it just gave out after a few more uses. I am going to test this theory by using my buddy's old 8800, I don't really believe that this power supply is the problem, if it is I sure hope that's covered under warranty since I bought everything from the same place.

If that doesn't work I will try pulling everything out of the case. I just really would like to know why it would just stop working on a reboot. It was running phenomenally, vista score of 5.7 limited by the memory which I expected to go up when got the 4GB.

If that does not work I will contact the reseller for an RMA. As stated earlier there are just so many possible problems and I don't have enough hardware to figure out what they are on my own.

Again thank you for your help, I prefer quality answers to many answers anyways.

The solution to this problem was a new video card.

So I have a theory about what happened... I used both my video cards in my old system with an Ultra X-Finity power supply. It was not a cheap power supply, but it was a brand no one really knows, which is definitely a bad decision. This power supply ruined my old board and both video cards. The memory and the hard drives remain ok though.

I don't care to thoroughly test my theory though since I have already replaced all of the components.

LESSON: Do not cheap out on a power supply, do your research and get a trusted brand name. It can destroy your computer so it should be trustworthy.