4850 bottlenecked by PCIe 16x 1.1?

[blazed]

According to this article from tweakown (http://www.tweaktown.com/articles/1472/1/page_1_introduction/index.html) 2x 4850 in Crossfire on a P45 setup (2x PCIe 8x 2.0) is bandwith bottlenecked, only somewhat at 1920x1200 and quite severly at 2560x1600.

Since PCIe 2.0 effectively doubles bandwith from PCIe 1.1, that should be the same as a PCIe 1.1 16x slot.

So the question is, is a 4850 bottlenecked at these resolutions with an older PCIe 1.1 16x slot? Single card setups or Crossfire, or maybe the performance loss is attributed to something else.

[Hardin]

It could just be driver issues, but I think we'll have to see more benchmarks to figure out the problem.

[jokers_greg]

hmm, luckily i have an X38 mobo on the way. i2x PCIE 2.0 x16 :)

[blazed]

All clues point to it being a bandwith problem, after all the issue only comes up when the most bandwith is needed at high and extreme resolution (1920x1200, 2560x1600), don't think this would happen if it was a driver issue, but who knows.

If someone could do a simmilar test with HD video encoding that might make things a bit clearer, untill now though I have to assume anyone with an older PCIe 1.1 16x slot their 4850 is being bottlenecked at those resolutions.

[FileAnt]

0.8x4=3.2
3.2/2=1.6 GB/s to each card

Just wait for PCI Express 3.0 ;)