Today's product tested all by itself even in it's default reference form kicks major ass for 249 USD. Now you can opt to drop another 50 USD for the 1792 MB of memory, but the reality is simple .. we tried hard, really hard to show the performance benefit of that phat increase in graphics memory. The reality however is that only at 2560x1600 at very hefty AA modes there's small difference measurable here and there in stringent conditions. Now we really had to reconfigure our games to be able to show you that difference.
So from that perspective, the additional 896MB of memory I'm afraid does not make much sense. Things might change though, I mean if history learned us one lesson, it's that the demand for framebuffer (graphics memory) doubles up roughly every two years. So in the long run the extra framebuffer will show some advantages. But sure it's relative alright.
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But if you'd ask me where I'd put my money, a faster clocked GTX 275 model, or a standard clocked GTX 275 with 1792MB of memory ? My money would be on the faster clocked product though. There's a direct, intricate and measurable effect in game performance related to the higher clock frequencies, opposed to trying the configure games to actual benefit from extra graphics memory.
