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pci-e 2.0 vs pci-e 16x ?
- Thread starter rz30
- Start date
Unless the application passes lots of extra textures through the PCI-E bus that don't fit in the graphics memory, the extra bandwidth is unused.
Even then, graphics memory bandwidth on high-end cards is a factor of several times higher than the PCI-E bandwidth.
Even then, graphics memory bandwidth on high-end cards is a factor of several times higher than the PCI-E bandwidth.
Soldato
16x pci-e 1 is aprox the same as 8x pci-e 2.0
All current cards should run fine on 16x pci-e 1, so 16x pci-e 2.0 is clearly overkill
I think this is why P45 was made with 2, 8x pci-e 2.0 slots for crossfire.
i hadn't thought of that and always assumed 8x Crossfire wasn't as good.
but if what you say is true then the P45 boards are the best ones to get
Soldato
P45 boards are slower when it comes to CrossFire since they're still PCI-E 8x 2.0 x2. Its ok for slower cards, but not faster ones.
A single high-end GPU gains a few FPS from PCI-E 2.0 16x vs 1.0 16x. However, CrossFire takes advantage of the extra bandwidth quite well, so if you're going to go for two cards then best go for X38/X48.
Why does CrossFire use the bandwidth? Couple of reasons:
1) All data needs to go to both cards instead of just 1.
2) The two cards need to communicate a lot, depending on the CrossFire mode. In the case of modes that only accelerate fillrate, the vertices from card #1 needs to be transferred to #2. At the end of (almost, depends on mode again) the framebuffer from card #2 needs to be transferred to card #1. There's also all sorts of other communications between the cards which, quite frankly, no one outside of ATI will know about.
The bandwidth is extra-critical for CrossFire since you won't get a frame output to the monitor until the transfers are complete. Hence you want that data transferred ASAP.
A single high-end GPU gains a few FPS from PCI-E 2.0 16x vs 1.0 16x. However, CrossFire takes advantage of the extra bandwidth quite well, so if you're going to go for two cards then best go for X38/X48.
Why does CrossFire use the bandwidth? Couple of reasons:
1) All data needs to go to both cards instead of just 1.
2) The two cards need to communicate a lot, depending on the CrossFire mode. In the case of modes that only accelerate fillrate, the vertices from card #1 needs to be transferred to #2. At the end of (almost, depends on mode again) the framebuffer from card #2 needs to be transferred to card #1. There's also all sorts of other communications between the cards which, quite frankly, no one outside of ATI will know about.
The bandwidth is extra-critical for CrossFire since you won't get a frame output to the monitor until the transfers are complete. Hence you want that data transferred ASAP.
