Benchmarks - PCI Express Throughput

X700 is ATI's fourth desktop PCI Express graphics chip now, and here we'll test to see if the performance of the PCI Express bus is up to the performance of X800 and X600, and compare it against the AGP performance from 9800 PRO.

TexBench (Downstream)

For the first of our two PCI Express tests we'll take a look at the downstream (from host to graphics card) performance using "TexBench". In this case we're testing up to 100 textures from sizes of 64x64 to 1024x1024, resulting in a maximum texture requirement of 400MB for storage, which exceeds the frame buffer space on all the boards here.

 

 

X700 XT 836.5 790.2 675.2 413.9 242.4
X700 PRO 752.5 749.0 728.2 661.0 309.6
X800 XT 1621.1 1621.1 1572.4 1429.7 364.9
X600 XT 595.6 592.2 578.5 535.4 196.6
9800 PRO 958.5 949.8 923.6 838.9 102.8

For the lower texture sizes the performance in Mega-Pixels more or less follows the expected fill-rate and bandwidth performance, with the 9800 PRO having greater throughput than the X700's thanks to is 256-bit bus and greater bandwidth. However, as we hit the 1024x1024 texture sizes the performance is switched, with the 9800 PRO giving the worst performance - as some of the textures are now being uploaded from system RAM the rendering performance is more reliant on the bus bandwidth, giving the advantage of the PCI Express boards.

Note that the X700 XT is showing lower performance than the X700 PRO in more cases as it has a lower frame buffer space, meaning that it has to address some texture data from system RAM even at the lower texture sizes, and even at larger sizes more texture data will be sampled from system RAM in total.

 

 

X700 XT 504.0 664.9 728.9 467.3 466.3
X700 PRO 504.0 664.9 762.2 453.9 458.8
X800 XT 332.5 801.3 726.7 453.9 457.9
X600 XT 504.3 672.0 728.7 441.5 457.1
9800 PRO 488.3 664.9 696.4 537.6 136.0

Looking at the performance in terms of quantity of data downloaded we can further see that all the PCI Express boards are downloaded roughly the same amount of data at 1024x1024 texture sizes, whilst the AGP board is showing about a third of the throughput.