HEXUS published a review on the ATI Radeon X1950 XTX 512MiB video card

With the same clock speed as X1900 XTX then, it's down to the new memory and a tweaked memory controller to give the X1950 XTX the edge. We can expect scenarios where memory bandwidth is gobbled up to see a gain with the new product. This includes high resolutions and where anti-aliasing & anisotropic filtering are cranked up, or to put it another way, the kinds of scenarios you'd subject a card like this to.

ATI Radeon X1950 XTX 512MiB Review