Radeon 9800 XT problem?

Okay you proved it is the monitor, but first sub the video cord from the computer to the monitor if possible, if okay! at this point you are looking at a LCD panel display problem, cheaper to replace than go through expensive repairs.

Memory failure on graphic card I suspect.
Hope this confirms your suspitions.

you can get anything in PCIe If your a mild to moderate gamer or just looking for a replacement I recommend using EVGA brand. I have had very good luck with the nvidia 9800 gts. They are older cards but still have quite a bit of potential. if your a heavy gamer use something nvidia GTX 260 or later they have the newer GPUs.

Check power supply section for bad caps with bulging top first, may be a sign of failing power supply: http://s807.photobucket.com/albums/yy352/budm/Viewsonic%20VX2235W/

This one is pretty clear. Your machine is a June, 2004 model. Your video RAM is bad. Video RAM is not user-replaceable on the Radeon 9800 XT, so you will have to replace the Radeon card itself.

An inadequate power supply might be your problem. Check the requirements on the video card and then look inside your case to see how many watts your power supply is putting out. If it is less than the number required by the card then this is likely your issue.

If you meet or exceed the amount necessary then it might be an issue with your drivers. Maybe sure you visit the ATI website for the most up to date and current drivers. Oftentimes many video card issues are solved by a simple driver update.

the error means that you do not have a power cod connected on the card or the power supplied by the PS is not enough for the card to run.

Remove power from the parts in the PC that you are not using anymore and try to reinstall the card.

worst case is getting another power supply about 600 watts

The memory on your card is beginning to fail. There is no repair for it, and it's time to let it retire.

You should be able to find a new 5700 or similar still in most computer shops. Pricing is the big problem with them costing far more then an equivalent PCI-e model.

This is a workaround - I too need a definitive answer. Symptom: black dotted vertical line 1/2 to 3/4" from leftmost image edge. I have begun adding single vertical line to my prints .25" from the left edge of the paper to force the "dots" off my print - this seems to have the desired affect, but it does not answer the cause or provide a true remedy (it will save many of your prints while we wait for complete solution). dkh

Sounds like a problem with the LCD assembly or cable. You may want to reseat the LCD cable at the LCD end. It could be a loose internal connector in the LCD assembly.
Ron-