RAID Controller for Z77

[unplugger71]

Goal: I want to add a RAID controller card to my system that supports RAID 10.

Current Setup:
ASUS Sabertooth Z77
Intel Core i7-3770k
Crucial 16GB DDR3 Memory
ASUS ATI Radeon 7870 Video Card (PCI Express 3.0 x16)

Motherboard states that I can do

2 PCI Express 3.0 x16 (x16 or x8/x8)
1 PCI Express 2.0 x16 (x4)
3 PCI Express x1

My question is this:
I like the Adaptec 6405 RAID card. I can insert it into slot two of the PCI Express 3.0 x16. However, this will make my first and second slots run in x8 mode. Will my graphic card's performance suffer?

Even though the motherboard says it only supports x4 on the third PCI Express x16 slot, is it possible that it will support x8 ?

Thanks!

 

[RealBeast]

You would have to use one of the 8x slots -- not the 4x. I run an Adaptec 6805 on an ASUS Z77. I don't notice any decrease in graphic performance, but then I'm not a FPS nutjob.

Make sure to get the package that includes the SAS to 4 SATA adapter connector as the connector alone is quite expensive.