Help in understanding the ASRock Extreme 3 z77 PCIE slot description

[dannyritz]

I'm thinking of getting the ASRock Extreme 3 Z77.
http://www.asrock.com/mb/Intel/Z77%20Extreme3/?cat=Specifications

I'm really confused by the PCIe slot description given on its specification page. I can't find a clear explanation online. This is the way its described.

- 2 x PCI Express 3.0 x16 slots (PCIE2/PCIE3: single at x16 (PCIE2) / x8 (PCIE3) or dual at x8/x8 mode)


I'm sorry if this is a silly question but will at least one of the slots run at PCIE 3.0 x16? Thats what I thought the first part of the line meant but then in the brackets its saying single at x16 pcie2, then it says x8 pcie3. Does this mean that the pcie3 slot will run at x8?

I'm planning on using a Sapphire 7950 and I don't want it to be limited in anyway. Thanks for your help.

 

[chugot9218]

Yes, the topmost slot will run at x16 BUT only if you are not using SLI or XFire, if you are using SLI both cards run at x8. I think this is only with SLI/XFire but I may be mistaken, it may also occur if any card (not just SLI gpu's) is plugged into the second slot, but I didn't think so. Maybe someone else can enlighten us.

 

[dannyritz]

I'm not planning on using sli or crossfire. So it will run x16 and pcie3?

 

[djangoringo]

1xPCI Express 3.0 x16 slots --->single at x16 (PCIE2)
1xPCI Express 3.0 x16 slots-----> single x8 (PCIE3)

Crossfire or sli, the two will run at 8x /8x

Just put the card on pcie2, you only get x8 if you put the card on pcie3.
As for loss of performance, either x16 or 8x pcie 3.0 i doubt that you'll lose any performance.

 

[dannyritz]

Oh! So thats what it meant. PCIE2 doesn't mean its PCIE 2.0, its just a number to describe its location.

So PCIE2 is a 3.0 slot that will run at x16. Thank you.

 

[dannyritz]

Best answer selected by dannyritz.