paopaw07 :
No, I just want to upgrade my existing z77 board asrock extreme4. Want to take advantage of the pcie x16 for my r9 290 xfire.
i'm sure you know what you are doing and you prolly know they is not a noticeable difference between 2x16 and 2x8 to invest in another motherboard. the added latency of the PLX chip (since the CPU lanes assignments will not exceed 16 PCIe lanes) will detract from any gains. the work around in the X79 or X99 platform of 40 PCIe lanes with no induced latency. but with only a possible 1.5FPS gain in gaming performance really is not smart money spent. PCIe lane saturation just might have extended past PCIe 2.0, but the 3.0 version the saturation point is barely used.
source
good luck and hope it works out to your advantage.
airdeano