strange artifacts on displays

I had similar artifacts with a ATI Radeon 9800 pro Mac Edition 256 MB
I reduced the ATI memory clock speed by 5% and they went away.
You can temporarily change clock speeds with ATIccelerator II from:
<http://mapage.noos.fr/campahunta/index.html>
You can make permanent changes with Graphiccelerator from the same site.

If it used to work, maybe you card is overheating (dust, or fan sticking).

you know, I pretty much have almost the exact same setup, though I think it's an ATI Radeon 9700 Pro, and I'm experiencing the same problems that started maybe 3-5 days ago.

it started with the power light blinking short-short-long indicating a backlight error which I believed because my monitor was looking darker on the bottom of than the rest of the screen, and then it started with the artifacts appearing over the icons specifically on the desktop, over dock, over menus and also with the mouse pointer.

I managed to open my machine, cleaned it up some, cleared it of any dust and at least managed to get the power light to stop blinking, though still dealing with the strange artifacts and wondering what I need to fix it.

now my question is, will this ATIccelerator thing really work, and if it's temporary, do I really need to try that Graphiccelerator that is being mentioned here, OR is the solution breaking down and buying another video card... ?

I had called apple at first with my backlight error, ironically 3 days after my 3 year warranty ran out, and they wouldn't do anything for me.

any suggestions on what the best solution is here... ? this is actually the first posting I've found of this problem from all my searching in the past couple days.

dual 1.42 G4 silverdoor model Mac OS X (10.4.6) 1 gb ram, ATI Radeon 9700 w/128mb DDR

now my question is, will this ATIccelerator thing
really work, and if it's temporary, do I really need
to try that Graphiccelerator that is being mentioned
here, OR is the solution breaking down and buying
another video card... ?

It's temporary in the sense that the clock speeds go back to the factory settings if you restart or sleep the computer. It does have an option to run at login. Graphiccelerator re-flashes the ROM on the card so the changes stay. Both of these programs are dangerous. A typing error could burn out the card.

Reducing the clock speed is a quick way of telling if the artifacts are software or hardware. If it is the card, you could try extra cooling (e.g a PCI fan card next to it), or permanently reduce the clock speed. Reinstalling the heatsink, with fresh thermal paste could help.

I was seeing artifacts a few times a day. I raised the memory clock speed by 10% for a few minutes and they became a lot more frequent. I then set it 5% below factory speed and haven't seen any since.