Memory should be as similar as possible (same manufacturer and batch as well
as spec.). Could cause grief if you added a 512 to existing ram. Use
SISoftware Sandra Lite or similar to perform repetitive checking to rule out.

Get the latest drivers for the graphics card, I had many issues with a
recent 6600GT install not resolved with NVidia drivers (and many forums
filled with similar comments - check http://www.guru3d.com/ - for info and
tools). My issues resolved by using the manufacturers (eg: asus in your
case?) latest drivers. These were the same version number as NVidia's, but a
different file size.

Check 3dmark website - forums reporting similar issues and solutions?

"Bob I" wrote:

> The video card and drivers.
>
> arcturus1111gr@yahoo.gr wrote:
>
> > I upgraded my son's pc with a graphics card 6600 asus and a 2nd
> > memory module 512 MB.
> >
> > During 3dmark05 or 3d mar03, I get some times blue screen.
> >
> > DVDshrink has no problems, so I assume the memory module has no
> > problems.
> >
> > During game play there are also no blue screens.
> >
> > Any ideas about what is most expected to fail, during graphics
> > benchmark???
> >
>
>