Well the results are in, fitting the ebay bargins into the machine cleared all the texture problems in ETQW.

There must be quite a memory problem with the 7900GT card, although it worked perfectly for most of the applications I run, ETQW may have been the only application that pushed the card a little too far, as it was the only application to show any problem. :'(
7900GT 3dmark06 3397 3DMarks (SM2.0 score=1355, SM 3.0 score = 1308, CPU = 1536)
Single 7900GS 3dmark06 4010 3DMarks (SM2.0 score=1610, SM 3.0 score = 1626, CPU = 1536) Run with 2 GFX cards installed not SLI'd.
Single 7900GS 3dmark06 4011 3DMarks (SM2.0 score=1614, SM 3.0 score = 1621, CPU = 1536) Run with only one 7900GS installed.
SLI 7900GS 3dmark06 6404 3DMarks (SM2.0 score=2915, SM 3.0 score = 2894, CPU = 1536)
All the above bench marks were run with a default desktop configuration to make sure they were comparable, I re-ran the single 7900GS card benchmark once I had reconfigured the system to run dual view with different resolutions on each monitor (as I normaly run my system) and this dropped the performance to 3919 3DMarks (slight drop but I am happy with it).
Although the 7900GS in SLI mode gives a great performance increase over the single card, I have decided to run a single card as I cannot live without having two monitors running (Game on one and desktop on the other) SLI only gives you the option to run a single monitor which sux IMHO.
So I have a new 7900GS card (only used for bench mark test!) and a slightly wobberly 7900GT card for sale, sensible offers on PM only.

, I may be listing these on ebay shortly

I think at the end of the day going the SLI route was interesting but not for me, so I may purchase a new 9800 when the prices drop a little, for the moment I will run the ebay 7900GS, if it packs up I have a spare
Thanks to all those that offered suggestions and advice.
