GA-P67A-UD4-B3 PCI-e single graphics lane problem

Hydrogoo · 20 Apr 2011 at 22:48

I have been through 2 of these motherboards so far and both have had the same problem. The PCI-e x16 lane is only operating at x8 when it rightfully should be running at x16 as I'm only using one graphics card (GTX580 Twin Frozr II OC) and there are no other PCI-e devices connected to my sytem. My question is: Is this working as expected or have I just been really unlucky and had 2 borked motherboards?

1Day · 21 Apr 2011 at 09:08

How do you determine that it is working at x8 speed?

Hydrogoo · 21 Apr 2011 at 09:13

Using GPU-z. I managed to get past the problem with help off the Gigabyte forums. Disabling eSATA and USB3 controllers fixed the problem. Seems that with the new SB architecture those features use the speed of the PCI-e lanes which dropped the graphics card to x8 instead of x16

1Day · 21 Apr 2011 at 12:01

Ah yes that is true they share the PCi-e lane.

Liquid · 21 Apr 2011 at 14:02

for one video card there should be 16 lanes available and down to 8 when there are 2 video cards installed only, one video card should give you 16x in the top slot. The e-sata isn't even off the native chipset. If it's not then there is indeed a problem.

1Day · 21 Apr 2011 at 14:41

It is the USB3 with that individual chipset - somehow the PCi-e lane is shared. Does not happen with P67.

Hydrogoo · 21 Apr 2011 at 18:40

I've looked at the block diagram for the board and it is indeed on the PCIe lanes, which is unfair to the consumer especially if you are paying for all the features on the board and having to disable some of said features to get the functionality where it matters to you.

Liquid · 21 Apr 2011 at 18:52

1Day said:
It is the USB3 with that individual chipset - somehow the PCi-e lane is shared. Does not happen with P67.

op's board is a p67 chipset board

pastymuncher · 21 Apr 2011 at 18:53

You are not going to lose that much performance with the slot running at 8x though. Maybe 2-4% on a single card.

1Day · 21 Apr 2011 at 18:55

Liquid said:
op's board is a p67 chipset board

Me bad thought I saw P55

pastymuncher · 21 Apr 2011 at 19:00

It's not a fault. This is why you should do your homework before buying a component. It's to do with Turbo USB3.0.

Taken from Gigabytes website:-

When GIGABYTE's Turbo USB3.0 feature is enabled, it provides the fastest possible USB3.0 performance by allocating PCIe lanes to directly connect the CPU and USB 3.0 controller chip. This provides approximately 10% better performance than when it is disabled and USB 3.0 traffic is directed through the chipset.
Note: Turbo USB 3.0 utilizes 8 PCIe VGA lanes, so it is only possible to enable it with a single graphics card running at PCIe x8 on P67 chipset motherboards, or while using Intel® HD Graphics from the CPU (i.e. no VGA card) on H67 chipset motherboards. It is an option for high bandwidth users.

See here, near the bottom of the page.

Looks like if you disable Turbo USB3.0 you will get normal USB 3.0 performance and get your 16x lane back.