SATA 6 - Mobos: 2nd PCIe 16x disabled?

[Newb888]

I have not been able to get any definitive answer on my question. With Gigabyte boards that have uSB 3 and SATA 6 capability, there are limits or bottleneck when running SATA 6 and USB 3. In particular, with the Gigabyte chipset when you use Turbo SATA3 / USB3.0 enabled in BIOS setup, 1st PCIex16 slot will run at x8 bandwidth and 2nd PCIex16 slot will be disabled.

Is this the same with Asus SATA 6 boards in particular the P7P55D-E lines and P6X58D Premium mobo?

 

[JackNaylorPE]

Is this the same with Asus SATA 6 boards in particular the P7P55D-E lines and P6X58D Premium mobo?

We got apples, oranges and pears mixed here

The P6X58D is a 1366 board; the P7P55D is an 1156 board.

1366 boards experience no limitations on PCI-E GFX lanes when SLI or XFire is added and remain at x16 speeds
1156 boards drop to x8 on the PCI-E GFX lane

To implement SATA III and USB 3, Gigabyte steals bandwidth from the GFX card lanes. When you insert a 2nd GFX card into a Gigabyte 1156 MoBo, it drops the USB3 and SATA II bandwidth to half .... that is 2.5 GB/s as opposed to the 50 Gb/s you get on the Asus boards.

http://www.tomshardware.com/reviews/usb-3.0-performance,2490-2.html

Keep it mind that there isn't really a lotta stuff you can buy at USB 3 and SATA III atm but then again why buy SATA III an USB 3 capable MoBos if they gonna be crippled in that manner ?

 

[Newb888]

I see no logic in buying a mobo that cripples your speeds ie. the gigabyte 1156 mobo. However, it was suggested elsewhere that even with the 1366 mobos with the the ICH10 south bridge has limits: http://media.bestofmicro.com/X58-diagramme,3-T-166025-3.gif

 

[JackNaylorPE]

The Asus 1156 Boards do not suffer from that problem.

http://www.tomshardware.com/reviews/usb-3.0-performance,2490-2.html