PCI-E x16 (X16 and X8 confusion)

The first one means it has two x16 size slots with one of them running at x8 speeds.

I can only assume that the board has a total of 24 pci-e lanes and chose to split them up like that.

The second board has opnly 16 lanes and allows you to choose either to use one running at full 16 speed or use two slots for crossfire but running at only 8x speed each.

The card will work fine.

Basically, pci-e lanes can only shove through so much data, so the more lanes you have the faster you can shove data through, it being a serial connection, each slot needs individual lanes rather than being able to share the same bus like a parralel one such as pci.

So a slot with 16 lanes will hae a theoretical throughput twice as high as a slot with 8 lanes, however, it does not mean you will see an increase in performance unless the data travelling to and from the slot exceeded the capacity of the lanes if you see what i mean.

That should be how it works.

Alright. Thank you very much, now I get it, but do most video cards push enough info that the x8 is keeping it back?

Alright, thanks a bunch for the info!

Tweaktown did a P45 vs x48 xfire comparison where they compared x16 and x8 PCIe modes for dual graphics cards. Sadly they only did a few tests but in most cases there was little of an impact on FPS, however, there was a FPS loss with Crysis and then with high AA/AF settings at the high resolution of 2560. I wish they would have tested with a lot more games, but it is what it is.

http://www.tweaktown.com/articles/ [...] index.html

If you are going to stick with a single GPU or lower resolutions with low AA settings, I wouldn't worry about it.