Originally Posted by anubis44
Your point may have some merit, but remember two things:
1) the graphics card must also be PCI-E 3.0 compliant, not just the slot, in order to get the PCI-E 3.0 bandwidth. Many users will be coming at this decision with a pair of decent PCI-E 2.0 cards they don't want to upgrade right away.
2) Many Z77 (if not all, I haven't done extensive research on this particular point) boards will revert to PCI-E 2.0 once you put a 2nd card (or more) into the system, so you lose the theoretical throughput of 3.0 once you crossfire or SLI anyhow. In a situation like that, I'd rather have the bandwidth of two full x16 PCI-E 2.0 lanes, than two x8 PCI-E 2.0 lanes.
1.) Yes, this is true, in order to utilize PCI-E 3.0, you would need a PCI-E 3.0 compatible card. The OP has chosen the HD7870, which is most certainly a PCI-E compatible card.
2.) This is incorrect, this may have been a limitation for the Z68 chipset, but a great deal of Z77 boards that have a PCI-E 3.0, support up to 16 lanes of PCI-E 3.0 bandwidth. You should take a look at some of the boards that Intel is offering. There are some boards that offer 32 lanes or more of PCI-E 3.0, this is achieved through multiple PCI-E 3.0 controllers. How the system is configured as far as which slots get what lanes of PCI-E 3.0 is different from board to board, however, most Z77 motherboards that support PCI-E 3.0 and are equipped with two slots will give you at least 16 lanes of PCI-E 3.0. The majority of the boards with two slots are X16/0 for a single card, or X8/X8 for Crossfire.
Here are some motherboards that support x8/x8 PCI-E 3.0
There are quite a few of the low budget Z77 boards that have 1 PCI-E 3.0 slot, and 1 PCI-E 2.0, you have to look around to find what I have mentioned in a sub $150 board. Once you break the $150 point, there are many more selections.
Additionally I would like to add to your comment about needing a PCI-E 3.0 compliant GPU in order to utilize PCI-E 3.0. In addition to needing a compliant GPU, you also require an Ivy bridge series processor in order to use PCI-E 3.0.