Congo,
The PC came with a pair of 256MB modules. We added a pair of 512MB modules. I had thought only the pairs had to be matched, not all four banks. Do you suggest we remove the original RAM?
Cal
I think he probably does. However, the performance difference between dual cahnnel & non dual channel is small, you'll gain more from more non-dual channel RAM than you will by having less RAM, running in dual channel mode.
Ideally, change so all the RAM banks match, but, as you won't find 2 512MB sticks that'll exactly match 2 256MB sticks, then I'd say your stuck with what you've got.
You could always solve the problem by matching the 2 new 512Sticks with 2 more identical 512sticks, replacing the 2 256MB ones, that would be my move. ;)
The 6800GS is a great card, as fast as the 6800GT but cheaper!
http://www.overclockers.co.uk/acatalog/ ... eries.html 
Posting drivel here since Jan 31st, 2002. - That long!
"He who laughs last, thinks slowest."