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AMD launches Radeon 7790: Meet the Xbox 720′s GPU
Its no coincidence that Bonaire answers some of the questions we had after the Xbox Durango GPU leak early last month. According to VGLeaks data, Durangos front end was capable of issuing up to two primitives per clock like Tahiti and Pitcairn, but the memory bandwidth figures pointed to a 128-bit bus. Now we have Bonaire a 128-bit GPU that merges those two capabilities in a single part.
Spinning a new GCN part for Microsoft allows for a smaller die, lower manufacturing costs, and explains why AMD CEO Rory Read calls AMDs console SoCs semi-custom designs. It makes no sense for AMD to build and launch another GCN part just to hit a market target but it makes a lot of sense for a cash-strapped company to design a new GPU that can target multiple markets simultaneously.
That said, the hypothesized Durango GPU isnt a perfect match for the HD 7790. Durango has 12 CUs for a total of 768 cores instead of the 14 CUs (896 cores) that the HD 7790 has. Clock speeds are also lower, at an estimated 800MHz. The 102GB of bandwidth between Durangos GPU and its 32MB ESRAM cache is a clean fit if we assume a 1600MHz cache clock and a 128-bit bus.
The Radeon 7790 anchors AMDs low end
Overall performance data on the 7790 is quite good, but price-wise, this card could clash with the HD 7850. At $149, 2GB cards based on Pitcairn are available for ~$180, and they offer significantly improved memory bandwidth as well as a modest increase in fill rate compared to the 7770/7790. The 7790 should compete nicely against Nvidias current Kepler lineup in that segment, though Team Green wont leave this space empty for long if it needs to hit back.
It would be nice to see a wider memory interface,
but the HD 7790 delivers 20-40% more performance than the HD 7970 for a 35% increase in price ($110 as compared to $149). Its a much better card than AMDs previous offering in this space, and it should compare much more favorably to previous GPUs like the HD 6850. This is a better-balanced GPU, period.