No Windows XP load screen after adding Asus EN8800GTX

What electrical connections did you connect to the new card?

2 x 6-pin PCI-E connectors from my PSU

I can see three possible problems.

1. The new card is DOA. It happens to the best of them. Try testing the card in a different computer and see if the problem follows the card. If it does, the card is bad. If it works, look back to your computer.

2. Assuming that the card works, the next place to look is the motherboard. It could be that the old 7900GT was starting to seem defective because the motherboard was dying. This is a bit harder to verify, but if you can try different pieces of your hardware on a different computer (one at a time, of course), you can find out if there are any other suspect parts. Also try running Memtest86 to make sure the ram is working and not causing a background problem.

3. The PSU might be dying and not sending enough current to power the video card. If so, the 7900GT might have started to seem defective because it wasn't getting enough power. When you try the 8800 GTX, the power draw goes over the top and the computer won't even try to boot normally. You didn't list the make and model of your PSU, so I don't know if its a quality one or one that is known for problems. Even if its a good company, it might just be getting old and breaking down.

Thanks for your answers.
1.) Well, if it is defective, then why does it boot perfectly fine until it tries to start Windows?
2.) RAM is fine, I tried memtest86 for several hours. I think the mobo is fine too but I have no other PC to verify it.
3.) THe PSU is brand new, bought it today, it's a Corsair 550W

PS: I tried booting my PC with Knoppix 5.1.1a and it had difficulties starting X, flickering between console and empty screen, then it re-tried it with xorg(vesa) and I got a picture and KDE started fine. Trying to switch to a console (CTRL+ALT+F2) killed it though and the same problem as described above occured.

Here is a link to a review for your card - http://enthusiast.hardocp.com/article.html?art=MTI1Miwx...

A couple of things come to mind.

1. The card is working fine but not installed into the MB correctly.

2. The card is working fine but the 6 pin connectors are not correctly installed.

3. The card is working fine but the power supply doesn't have the juice to support the entire system with the new card.

4. The card is working fine but prehaps some setting in the bios is not enabled to allow the card to function.

5. The system is working fine the new card is installed correctly with correct electrical connection but the card is somehow defective/damaged/doa out of the box.

Is this your MB? - http://www.msicomputer.com/product/p_spec.asp?model=K9N...

Something that I saw reguarding the specs for this MB is "One PCI Express X16 slot (supports PCI Express Bus specification v1.0a compliant)". I wonder if the new VC requires another spec. I wasn't able to find anything about that. The asus site was down when I checked it.

Thanks for the reply.
1) I checked and it is definitely installed correctly
2) Well, there is not much you can do wrong when clipping those to the card
3) According to the PSU and the Asus manual, it does.
4) Any idea, what setting that could be?
5) Well, that could be but then why does it show picture at all?

I asked at the store specifically and they told me, that my MB supports this VC.

You really need to try it on another motherboard that has a pcie slot. This is just how troubleshooting works; isolate the problem by process of elimination. However, from what you're describing the card sounds DOA, either that or it's time to upgrade your power supply. Also, as far as using the standard vesa drivers in knoppix, or any distro of linux, they are extremely basic, and do very little to tax the video adapter, and being about to start X with them is pretty inconclusive.

Also, as far as testing your powersupply, you might try unplugging/taking out anything you don't need to boot into windows, ie sounds cards, extra harddrives, optical drives, extra fans, etc. Although this can only explain so much, it might just happen that you realize Windows fully boots once you try it, because during start-up from what I understand power use is really high.

As I wrote above, the PSU is brand new and excels the requirements by the graphics adapter. You are right of course, I should try it with another PC but I don't have one available. :-(

As Sailer said above, try the VC in another system. That will determine if the VC is working correctly providing the second system can support the new vc, lol. Try a replacement PSU if possible. The mem could be a problem but down the list of possibilities. One of three things is the problem, VC, PSU or the MB probably in that order. The new vc is stressing the PSU more than the old vc. Were there any static electrical shocks at anytime during the installation? Was the Power cord unpluged during the installation? You say the the system runs fine with the old vc installed?

No, there weren't. Yes, it was. Yes, it does.
I could try the old PSU for a moment, although it does only give 29A on 12V but maybe it goes far enough to rule the PSU out.

OK, going through the list.

1.) The video card could be good enough to get through the BIOS, but then fail while Windows starts. I have an old 1900 XTX video card that will run fine while booting up and running light programs, word processing, etc, but if I try to play a game, it crashes out. There are many different ways that a card can exhibit failure. I see where you don't have another PC available, but do you have any friends that might allow you to try it on theirs? If not, then nothing else is easy when it comes to testing parts.

2.) Good to know that the ram is fine. That eliminates a potential problem source.

3.) The Corsair 550wt PSU is a good one. Unless it is defective, and its unlikely that two or more parts have gone bad at the same time, it can be eliminated as a problem source as well.

Unfortunately, this puts things in the harder to diagnose area. Its back to the fact that the 7900GT was starting to show problems and now the 8800 GTX is not functionally working at all. Given that you've checked the wiring and confirmed its correct, I'd look to a failing or bad motherboard next. It may have been having trouble in the PCIe slot and with the higher end 8800 GTX. If your motherboard has two PCIe slots ( looked up MSI and they list a number of K9N motherboards, so don't know which model you have), you might try the video card in the other slot and see if it works there.

The last thing I can think of, and this is where nothing else can be easily found, is to take the computer in to a shop along with both the 7900GT and 8800 GTX cards and explain the problem to them and have them test the machine. That can be expensive, but it can end up cheaper than buying a lot of unneeded parts and still not figuring out what's wrong. At this point, though, I'd look more to a defective motherboard, followed by a defective video card.

Unfortunately, I have no friends nearby that have a system where I could test it. I am thinking about it but I can't recall anyone.
I might have to take it back to the shop and ask them to test it for me, they should be willing to do so I hope.
Your theory about the mainboard sounds plausible, I need to test it. I got the MSI K9N-Neo-F, it only has one PCIe x16 slot I'm afraid. :-/