ASUS Sabertooth Z77 - Black PCIe x16 slot question

[UpGrade01]

Hey guys,

I have a ASUS Z77 sabertooth as the title suggest and I'm looking to get a good raid controller for it. Most good raid controllers appear to be x8 and I know physically an x8 card will fit into a x16 slot but on ASUS sight and the manual it states the following.

2 x PCIe 3.0/2.0 x16 (x16 or dual x8) *2
1 x PCIe 2.0 x16 (x4 mode, black) *3
3 x PCIe 2.0 x1

Does this mean it will only support a x4 card or is it stating that if I threw another video card for tri-fire/tri-sli in that slot the video card would only run at x4? or it is stating that no matter what a x1 or x4 card will only run in that slot no matter what. If that is the case will I still be able to throw in an x8 card which would just be bottle-necked by the less through-put or is the a potential that it will damage the card?

Thank for all your help.

 

[c123456]

Answer is in the instruction manual found here: http://support.asus.com/download.aspx?SLanguage=en&m=SABERTOOTH%20Z77&os=30

 

[wdmfiber]

It's hard to bottleneck a modern GPU via PCIe slots. Hopefully the next generation cards(20nm) will be substantially more powerful. If you put a Radeon 7970 or GTX 680 in an old PCIe 1.1 x4 slot, the cards are powerful enough for there to be measurable bottleneck. But typically with modern builds in SLI/crossfire, it's the 4th GPU that doesn't add much more.
http://www.techpowerup.com/reviews/Intel/Ivy_Bridge_PCI-Express_Scaling/23.html