I have looked around but I haven't seen any tests, Does anyone no the performance effects of using a multi GPU setup on a mobo with two x16 express slots versus two x8 slots. because dual x16 mobos are often several hundred dollars more expensive than other mobos
PCI Express, crossfire and SLI
- Thread starter new_guy
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You are talking about the PCI-E Lanes, which basically determines the how much data can be transfered to and from the GPU, the number refers to how many lanes are available. If the GPU supports PCI-E 2.0 each lane can transfer 250MB/s to or from the GPU (old PCI slot lanes did not have Bi-Directional lanes), so each lane can be transferring 500MB/s of data so for a PCI-E x8 slot this would mean that 4GB/s of data can be transferred to and from the GPU (You can work out the x16 slot). But not all graphics cards support PCI-E 2.0 in which case the transfer rate would be half of what PCI-E 2.0 is.new_guy said:
So Performance wise, it doesnt usually have much of an impact considering in x16 express slots the amount of data being transferred rarely hits its limit. As for this to happen it would have to be constantly sending data through all lanes.
Hopes this helps!
I was merely explaining how the lanes in expansion slots work, as it helps understand what x16 x8 and the like means, and how they may effect performance. Your statement about nVidia and ATI cards being x16 compatible is true, but you miss out the fact that even though a Motherboard may have 3 x16 slots some of them might not work at full capacity. Take my Motherboard for example Gigabyte GA-P55A-UD3, has 2 PCI-E x16 slot, one works at the usual x16 rate but the other only works at x4 due to a power issue in the motherboard (would like a new shiny Mobo but no money).rEvolution said: