To update anyone with an interest in this: d2thez sent me an eVGA 5900U bios which I'm able to clock up to 500 / 900 and get better performance than I had with the Leadtek 5950U overclocked as high as it could go (which was only about 490 / 880 ) - plus I don't have the crosshatching which it seems any 5950U Bios causes on my V9950U card.
Many thanks d2thez
