Video Cards & GPUs News - Page 419

However, there is just one thing that does not hold ground in the story - and that is that RV870 should use 512-bit memory interface and GDDR5 memory. I may be forced to eat my own words, but no, ATI RV870 will not bring 512-bit memory controller. RV870 will feature much improved 256-bit memory controller, and it will offer bandwidth of some 150-200 GB/s per GPU. When you combine the two GPUs, possibly on the same substrate, you will get 512-bit memory controller...in a way. 512-bit memory controller with current GDDR5 memory (900 MHz QDR, e.g. 3.6 "GHz") yields 230 GB/s. And that is the amount of bandwidth GTX280 would have if nV went for GDDR5 instead of older GDDR3 memory.

Nvidia's next-gen part will however, bring 512-bit memory controller coupled with GDDR5 memory, offering insane amount of bandwidth - 200-250 GB/s, to be more precise.

As you can see, the FPS changes linearly with the number of shaders in the GPU. Please note that this is data from some real empiric testing. All those ten tests were performed with a real running HD 4850 (running at HD 4830 clocks for better comparability), without reboot in between, shader count was changed on the fly.

If you look back up at the first graph, you can easily see that the AMD 4830 result matches the result I got with 560 shaders and the PowerColor 4830 matches 640 shaders.

This test confirms that 3DMark06 Perlin is a valid test to determine the relative shader performance of a RV770 card. It also confirms that the register contents reflect the active number of shaders and that AMD's sample has the shading power of a HD 4850 with 560 shaders and that the PowerColor card is equally as fast as a HD 4850 with 640 shaders.