Can I use 2 x1900XTX or does one have to be X-fire edition?

[zarzar]

Can I build system using 2 x1900XTX or does one have to be X-fire edition? Board will be with the the xpress 3200 chipset.

Does anyone know?

Thanks!

 

[cleeve]

Yes, you need one X-fire edition board for Xfire to work.

 

[dvdpiddy]

what cleeve said but if you go x-fire get the xt cause the xtx wont give you that much performance increase anyway and when you x-fire an xtx and an x-fire master card the xtx scales down to xt speeds which are the crossfire master cards speeds and you lose performance unless you oc the crossfire mastercard but then you void your warranty

 

[ltcommander_data]

I think it's a great question. Theoretically 2 X1900XTX should work in Crossfire mode just like 2 X1600XT will. The RV530 core doesn't have an integrated compositing engine since that would come until the RV570, so it's probably enabled through driver support. I would think 2 X1900XTX could work the same way as long as the driver supports it.

However, this is just for the sake of argument only. 2 X1900XTX could never work performance-wise on the older Xpress chipsets because they would be terribly bandwidth starved trying to communicate through PCIe x8 slots. Even the x16 slots in the Xpress 3200 aren't enough to feed 2 ultra-high-end X1900XTX. A Crossfire Edition with the external link and compositing engine is required for optimal performance.

 

[zarzar]

Excellent answer; I think it makes perfect sense. Thank you!

 

[nottheking]

I think it's a great question. Theoretically 2 X1900XTX should work in Crossfire mode just like 2 X1600XT will. The RV530 core doesn't have an integrated compositing engine since that would come until the RV570, so it's probably enabled through driver support. I would think 2 X1900XTX could work the same way as long as the driver supports it.

However, this is just for the sake of argument only. 2 X1900XTX could never work performance-wise on the older Xpress chipsets because they would be terribly bandwidth starved trying to communicate through PCIe x8 slots. Even the x16 slots in the Xpress 3200 aren't enough to feed 2 ultra-high-end X1900XTX. A Crossfire Edition with the external link and compositing engine is required for optimal performance.

Well, it's also a curious question as well; in theory, there should be sufficient bandwidth through the PCI-express bus alone for even top-end performance. After all, presuming, say, a standard resolution a gamer would want with a CrossFire or SLi setup would be 2048x1536, with 64-bit color depth, (FP16 for HDR) that would be 24MB of size for each frame, or only some 1440MB per second needed even if one card was sending over 60 frames for each second. (optimal would obviously be 720MB/sec) Of course, I may have been mistaken on how multi-sample AA playes into this, (it may be, if using x6 AA, that baloons to a minimum of 4,320MB/sec of bandwidth usage minimum) but it's still generally considered that even a meager 2GB/sec is typically more than enough graphics card bandwidth, yet PCI-e x16 provides twice that.

Personally, though, I wonder when ATi, which already packages integrated graphics at least with the Radeon Xpress 200 (if not the CrossFire Express 3200 as well) figures out that perhaps the best solution is "premium" boards that come witha pair of DVI ports (for high-res digital signals) and simply has the compositing engine on the motherboard, and can simply recieve from each of the cards, and output off of the motherboard itself. This would, in theory, eliminate any problems caused by having the cards cross-communicate.

Atill another technology I wonder about is the "HTX" hyper-transport slot; that offers a supposed maximum of 22.4GB/sec of bandwidth, which is about half the RAM bandwidth of the X1900XT. It is also connected directly to the CPU, so the latency problems some have attached to PCI-e versus AGP are also eliminated. I wonder if that might be used for graphics cards anytime soon...