Wow! So many configurations without positive results. Hmmm. Hang in there niteshadw. Try this config. Go into your BIOS and see if your video cache is enabled. If so, disable it. If you have a UC and USWC option, choose UC. If your graphics are still corrupt, uninstall your video drivers and the use driver cleaner to unistall the remaining files. Also uninstall your AGP drivers and get the latest AGP drivers from your motherboard's website. I don't remember if you've already stated that your BIOS is updated along with your motherboard drivers. If not, update everything. After all this is done and you still have graphic corruption, it may be best to do a format. I hate to even mention a format because so many people depend on formatting even for the most simple of problems. But sometimes it is necessary. Darn it! You should not have to format your whole system just for a video card!
I've talked to people that have underclocked their cards and they have met success. Your card should work at normal clock speeds though. Mine is working normally. I would try BillyJak's suggestion as well. You can easily underclock your card if you install the Omega Catalyst drivers. The option will be located with the rest of the ATI tabs that were mentioned in previous post. Please do not go overboard with over or under clocking. Underclock in small increments if you decide to try that option.
Take care niteshadw,
I'm going to say a small prayer. 🙂