PCIE 8x vs 16x

[coelo]

Hi,

Using the new UEFI uh1 BIOS on the gigabyte GA-Z68 UD3H-B3 board I do not see any option for USB 3.0 and USB 3.0 Turbo.
The fix to get PCIe to run at 16x rather than 8x used to be to turn off the USB 3.0 in the BIOS, but now I don't even see that option.
So, my card is running at 8x on a16x lane.

It is not the end of the world by far, but I was just wondering if anyone knew how to resolve this issue on the new UEFI BIOS.

I saw no USB 3.0 options under peripherals in the BIOS, did they hide it somewhere else?

 

[ggeorge]

Hi,

Using the new UEFI uh1 BIOS on the gigabyte GA-Z68 UD3H-B3 board I do not see any option for USB 3.0 and USB 3.0 Turbo.
The fix to get PCIe to run at 16x rather than 8x used to be to turn off the USB 3.0 in the BIOS, but now I don't even see that option.
So, my card is running at 8x on a16x lane.

It is not the end of the world by far, but I was just wondering if anyone knew how to resolve this issue on the new UEFI BIOS.

I saw no USB 3.0 options under peripherals in the BIOS, did they hide it somewhere else?

USB shouldn't have anything to do with the number of PCIe lanes the graphics card uses. This is typically determined by the number of cards and which slot you have them in. A lot of motherboards (like this one) have only the first slot being a true x16 slot and the others are x8 or x4 slots, despite having an x16 physical slot. This is due to the limited # of PCIe lanes on the socket 1155 chips (only 16).

So if you have it in a slot other than Slot #1, that would be why you aren't getting x16 performance.

In any case, in most tests I've seen, there's only a small difference in performance, between a card (presumably a graphics card) running at x8 and x16.

 

[coelo]

The forum says otherwise...

http://legacy.tonymacx86.com/viewtopic.php?f=54&t=52572

 

[Juggernaut1987]

This question isnt something you should ask here I feel. Maybe Gigabyte changed an option in their new bios that enables 16x by default, hence removing the turbo mode option from the Bios.
There isnt a way to find out what your PCI-E slots are running from any OS if im correct so I would mail Gigabyte customer care about this. They might have the technical knowhow to answer this question for you.

 

[ggeorge]

The forum says otherwise...

http://legacy.tonymacx86.com/viewtopic.php?f=54&t=52572

And I can't find ANYTHING other than that thread which says anything about needing to disable USB3 to enable x16 lanes on this motherboard.

This DOES appear to have been an issue with intel's P55 chipset, but that is not what you have on this board.

However I DO find this for your motherboard.

Expansion Slots
1 x PCI Express x16 slot, running at x16 (PCIEX16)
* For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot.
1 x PCI Express x16 slot, running at x8 (PCIEX8)
* The PCIEX8 slot shares bandwidth with the PCIEX16 slot. When the PCIEX8 slot is populated with a PCI Express graphics card, the PCIEX16 slot will operate at up to x8 mode.

Which is a VERY common arrangement with a Z68/Z77 motherboard. The other PCIe slots are not TRUE x16 slots. So again I ask.

Do you have the graphics card in slot 1.

Or do you have some other PCIe cards installed in the other PCIe slots.