[G4] Artefacts with ATI 9800

[Rory Gillies]

Hi,

I have a Sawtooth AGP G4 (originally a Gigabit Ethernet/400MHz single
processor) that has been upgraded to the following:

Sonnet 1.4GHz G4 processor
896MB RAM
Internal 16xDVD Rom/48x48CDRW (Apple Supported)
120GB 7200rpm HDD
500GB FW 800 External HDD
USB 2 PCI card
FW 800 PCI card
External FW 16x DVD+-RW DL
Mac OS X 10.4.7
17" CTX TFT (standard VGA connector)

This machine was running very well (actually performs better in some task
than my G4 1.42 Mac mini) but the original ATI Rage 128 16MB graphics was
proving to be a bottle neck. I recently purchased an ATI Radeon 9800 Pro Mac
Edition card, and although everything runs fine I get faint vertical stripes
across the display. When using apps like Photoshop or iPhoto, as soon as any
adjustments are made to the active image it appears to pixelate and is
impossible to edit.

The lines are clearly visible when the flurry screen saver is running, and
also in the iTunes visualiser (although not as bad). 3D apps work fine, but
instead of the banding there are noticeable artefacts around moving objects.
I'm running the latest ATI drivers and firmware for the card.

Has anyone experienced anything like this with a similar setup? I have tried
everything adjustable possible, and am suspecting a hardware fault with the
card (nothing else with AGP to test it on). The other possibility is the
stock power supply in the Mac isn't producing enough grunt - any ideas?

Sorry for the very long post, but I thought I'd get a second opinion before
returning the card.

Cheers,

Rory