As you probably remember, the point of this test is in sending a certain amount of data from the system memory to the graphics memory and back again, the size of the transferred block varying from 64KB to 4MB. The utility loads the memory controller, the graphics bus and the CPU-chipset link.
We’ve got some curious results here. The RD480-based platform is quite confidently ahead when transferring data from the system memory into the graphics card’s and irrespective of the data block size. We performed the same test with a Radeon X1900 XTX down-clocked to 500/1000MHz and with a Radeon X1800 XL and found that the graphics memory frequency was not a limiting factor. The CrossFire Xpress 3200 is behind for some other reason.
It’s even more interesting with the backward transfer: the new ATI chipset is much better than the older one, but only with a Radeon X1900 and irrespective of the latter’s clock rates. When we installed a Radeon X1800 XL, the results went down immediately to the level of the Radeon Xpress 200 CrossFire Edition!
Unfortunately, we can’t really explain this and we used a similar utility, Serious Magic Texture Download Benchmark, to verify the results.
Love at First Touch: ATI Radeon Xpress 3200 Review (2006-03-28)