I meant 'not even see memory on the video card above 512MB'
That is not true. I have a Precision 690 and i have a Sapphire Radeon HD 6570 2GB VRAM and it reconizes exactly 2GB...
It is just outdated info. When the 690 came out, the best cards where GT8800's with 512MB of VRAM.
It even supports the new AMD Radeon HD 7970 card series. They have 3GB of VRAM.