I am trying to install an x1650 pro video card in my sons dell dimension 4600. I am not a techy, but I can usually follow instructions and get the job done.

I read in another forum that this AGP card is compatible with this computer.
I have actually tried two different vid cards and both of them are not recognized by the monitor. I confirmed compatibility of the other card awhile back but never installed it.

This is the really weird thing, while the video card is in the slot, the monitor will not work with the onboard video either. I put it back in the regular spot and nothing. This happens with both video cards, the monitor stays black. Take the card out, put the monitor in the regular port and it works fine.
BTW The AGP is 8X and so is the card.
Now, I have tried to disable the onboard video in the setup, but it only lets me pick "onboard" or "auto" for video and won't let me disable. I can disable in the device manager, but not sure I am actually disabling the correct thing.

I previously had a 9800 pro video card in this computer. At that time I was able to disable the onboard video in the setup/bios. I had to take it out because although it worked, it got crappy after a short time due to the too small power supply. I couldn't figure out how to change that in the dell so I sold the card on Ebay.

Now I realize I have to upgrade the power supply and I have one that will work, and I have figured out how to do it, but I don't feel like doing that until I get the video card installed.

For the life of me, I cannot figure out what would be causing this problem. I have had help from people who know alot more than me and they can't figure it out. BTW, The fan is running on the card, but the monitor (and another, I tried two just in case) doesn't recognize the card at all.

I am sorry for the lengthy post, but figured you would need info for this...Any idea's what would cause this???