Okay, as far as I can tell it's a problem with the firmware. The test: <<Which unfourtunately I've no time for at the moment, if one of you blokes'd do it for me an' post the results, I'd be eternally grateful>> Run a benchmarking tool<<Such as 3dmark, whatever>> with both strips in, and then with one in. If it's not just an illusion of better performance we're seeing<<Which I doubt>> then the benchmark will show it.
As a second test, I'd like to see if you also recive better performance with one 512 than with two, but I've no 512 strips hanging around to find out with.
An' if it is verified by the benchmark, I've only this to say: Whisky Tango Foxtrot Alienware!
If nobody gets around to testing this, I may be able to in...perhaps a month or so, what'd be great is if the Mothership tested it out for us an' posted the results<<As yet I've not called them, Busy life>>. Or at least if one of the kindly AW folks'd let us know their ideas on the matter.