PCI-E 16 slot... at only x8?

So I got this mobo... GIGABYTE GA-G31M-ES2L I didn't realize it had only a x8 slot on the PCI-E 16 (it didn't state that in the stats of course, I found it out digging around on Gigabytes website). This is not a xfire/sli mobo, this is the only GPU slot on the board.

So, how much will this slot hold back a 4830, 4870, or GTX 260/280? Basically what I am wondering is will a faster video card be held back by this slot to the point it makes more sense to buy a cheaper, less powerful card.

The newegg page lists it as one PCI Express x16 slot. The Gigabyte page linked lists it as "PCI-Express X16 (X8 )". What is up with that?

Ok, did some research on the g-31 chipset. It looks like its a PCI-E 16 1.1 slot from intels spec sheet....

So the stats on the g31 chipset allow for full 16x 1.1 slot, BUT... what I dont know is- does that make this mobo automatically 16x, or could Gigabyte be saving a few pennies by making it a 8x slot? I dont know exactly how that works.

It looks like matrix563 is right, its 16x OR 8x, but would like some further clarification if anyone knows.

Ok, this gets weirder. I e-mailed Gigabyte to ask them if it was x8 or x16. They answered the question that the chipset holds it back to x8. Now, I know the g-31 chipset doesn't limit it to x8.

So I downloaded GPU-Z and it says... Bus Interface-PCI-E 16 @ 16. So who is right? Does GPU-Z actually read the physical stats of the mobo?

chocobo7000

Trust Gpu-Z or if you want to go to bios and check it...

Cya