First of all let’s reveal the default clock speeds of the XFX 6800 Ultra 512Mb
.

The core is clocked at 430Mhz. The memory is clocked at 1050Mhz.

This is compared against an XFX 6800 Ultra 256Mb stock-clocked at 425/1100Mhz.

This is the test bed:

testbd XFX GeForce 6800 Ultra 512MB Review

The display driver settings were all left at default unless
stated in the tests.