Graphical corruption on new build

[robz]

Graphical corruption on new build *UPDATED*

I've just put together the following

Tagan 550W PSU
AMD 64 3000+ Venice
*A8N-SLI
*OCUK 6800GS
512mb Geil Value
*1 x WD 250Gb 16mb
1 x WD 250Gb 16mb

*Denotes items bought 'B Grade' from OCUK

Managed to setup the 2 HDDs in a raid-0 config, and installed windows xp MCE no problem.

Booted into windows, installed the 81.xx drivers recommended from nvidia.com for Windows MCE, and restarted no problem. Installed the chipset drivers and the ntune drivers, restarted, and the graphics during bootup is extremely corrupted. Gets to the windows loading bar(still corrupted) and the screen goes into power saving mode.

I can't even get into safe mode. Is it worth formatting and starting again, or is it likely to be a problem with 1 or more components?

EDIT

Moment of madness there. Not quite sure how I thought I'd format it with no graphics card.

 

[robz]

Right. I left it for a while, and tried again. Booted up with no corruption at all.

Formatted, re-installed, and installed chipset and video drivers, and everything was fine.

It doesn't seem to like restarting though. A couple of times it would just hang on the 'Windows is shutting down' screen. It is after these hangings that the corruption returns. If its left for 10 minutes or so, it seems to boot up with no ill effects.

Anyone shed any further light on the likely cause?