ATI Radeon HD 4000 Series discussion

[Kai Robinson]

Can someone help clear this up? I'm having a tough time trying to figure out how cards communicate over crossfire...and P45 issues - i was under the impression that the bridges that the cards connect to each other with, share data between them, but all the fetching of the textures and the like, are done over the PCIe bus, correct?

Now, the other thing is with P45. A single PCIe 1.0 16x slot provides 4GB/sec of bandwidth, and a single PCIe 2.0 16x slot provides 8GB/sec of bandwidth....P45's having PCIe 2.0 8x/8x setup for crossfire is the same as having a pair of PCIe 1.0 16x slots, as each PCIe 2.0 8x provides 4GB/sec of bandwidth, correct?

So why is it then, that in the Tweaktown review that was done that pitted the P45 vs the X48 have CF on the P45 tank so badly when it got to Crysis, even at low resolutions? The mild 10% performance hit i can fathom, and as well in the 2560xstupid resolutions they were using, but from 35fps at 1280x1024 to 21fps? I'm sorry but i dont buy that. A single HD4850 hands my 8800GT its own arse at 'Very High', and my 8800GT gets 29.03fps at 1440x900... so here i am wondering, is that review flawed, or have i dropped into a coma and all of this is some elaborate way of my mind telling me that nothing is real and i need to wake up....?

If its the former, can someone on the forum please do an independant CF test of P45 vs X38 (DDR2 to DDR2, not DDR2 to DDR3) and test Crysis? And if its the latter, can someone please ring Gene Hunt?

(cue David Bowies "Life on Mars")