Nov 2, 2011
Alright im looking at building a comp mainly for gaming ive pretty much settled on i5/Asus mobo but im just wondering is it important to get a mobo with PCI 3.0? or should 2.0 be alright? I mean the mobo im looking at currently is a Asus P67 but idk i went back and was looking at the Z68's because they have 3.0 and was wondering if i should just get that so when 3.0 cards start showing up ill be ready? And on a side note 3.0 are back compatable with 2.0 correct? Andddd i know this is probably a horrible newb question but PCI 2.0 slot can work 2.1 cards correct? TY so much for reading the lengthy post and appriciate any feed back!

there are a few x68's with pcie 3, so you may aswell get it its all backward compatable. Its porbably more important for a crossfire setup as you will get more bandwidth between 2 cards when pcie 3 cards come out. so instead of 8x/8x pcie2 speeds you will have 8x/8x pcie3 speed which is equivelant to the current 16x/16x pcie2. As far as i know there arent any pcie 2.1 motherboards, only 2.0. there are 2.1 cards which will make use of some features of pcie3. To get the pcie3 you need an ivy bridge cpu, soon to be released.
PCI-e 2.1 adds some error checking algorithms to PCI-e 2.0. As stated by iam2thecrowe, there are no PCI-e 2.1 slots, it has only been implemented on the video card itself.

As long as you are using a single card with a single GPU core you do not have to worry about bandwidth limitations with a PCI-e 3.0 card in a PCI-e 2.0 slot. There is still plenty of bandwidth available in the PCI-e 2.0 slot even with the current fastest PCI-e 2.0/2.1 video cards.

I currently use a PCI-e 2.0 Radeon HD 5850 in a PCI-e 1.0 slot and I am bottlenecked by the PCI-e slot. PCI-e 2.0 has 2x the bandwith of PCI-e 1.0. Therefore, you can say that my PCI-e 16x 1.0 slot is equivalent to a PCI-e 8x 2.0 slot.