PCIE link speed for my graphics card isn't 16x

[mikeymikec]

My board: ASUS M4A89GTD PRO/USB3, latest BIOS
Graphics card: ASUS GeForce GTX 750Ti
OS: Win7 64 SP1

I've just noticed that the link speed being reported by CPU-Z is only 8x despite 'max supported' being 16x. I once encountered this with my 5770 and the same board, but I fixed that by following the manual's instructions regarding the use of a VGA switch card and having the graphics card in the correct (yet not that logical) slot, so obviously that's not the problem here.

I suppose I can update to the latest graphics drivers, but it seems unlikely to me that this is the root of the problem.

Any suggestions would be much appreciated!

- edit - GPU-Z reports the link speed as PCI-E 2.0 x 16 @ x8 1.1 while the card is mostly idle, and it changes to x8 2.0 during the render test.

 

[inachu]

My board: ASUS M4A89GTD PRO/USB3, latest BIOS
Graphics card: ASUS GeForce GTX 750Ti
OS: Win7 64 SP1

I've just noticed that the link speed being reported by CPU-Z is only 8x despite 'max supported' being 16x. I once encountered this with my 5770 and the same board, but I fixed that by following the manual's instructions regarding the use of a VGA switch card and having the graphics card in the correct (yet not that logical) slot, so obviously that's not the problem here.

I suppose I can update to the latest graphics drivers, but it seems unlikely to me that this is the root of the problem.

Any suggestions would be much appreciated!

- edit - GPU-Z reports the link speed as PCI-E 2.0 x 16 @ x8 1.1 while the card is mostly idle, and it changes to x8 2.0 during the render test.

I have seen manufaq not staying on any industry standard when it comes to PCI - PCIE coloring scheme using brown, black, white, blue.
We tend to think the blue PCI-E would be the X16 slot but the only way to be sure is to read the motherboard manual.

Next up to try is as you say you did or will try such as the BIOS and video driver update.

Reply back please after you have updated the video driver.

 

[mikeymikec]

There are two PCIE 16x slots on this board, and I had the 5770 working at 16x link speed in the one I currently have the 750Ti in. The other has the VGA switch card in as the manual specifies.

 

[Smoblikat]

I own this board, and as long as you run the card in the top PCI-e slot, it should run on X16. I used to play around with the VGA switch card and putting it in the lower slot, but im running my 4870X2 in the top PCI-e slot and it recognizes it as X16. Try a CMOS reset.

 

[inachu]

?

 

[Ketchup]

Probably a silly question, but are you using the blue slot or the gray one? The only reason I ask is because the second slot(blue) is your primary 16x slot, which is the opposite of most boards.

The M4A89GTD Pro/USB3's PCIe and PCI slot setup is very unusual. From top to bottom we have a PCIe x16 slot (white), followed by PCIe x1, PCIe x4, a second PCIe x16 slot (blue) and two standard PCI slots. When I initially saw this design I was surprised that Asus would have chosen to obscure a PCIe slot rather than a PCI one when installing a dual-slot video card, but as it turns out, this is not the case. Following the colour-coding of the rest of the board, the primary graphics card slot is actually the second (blue) one, and to make things even odder you need to leave the provided daughter card installed on the first slot to give a single card its full x16 bandwidth.
Read more at http://www.trustedreviews.com/Asus-...features-continued-page-3#vBqEizeZDHWBrbX9.99

 

[mikeymikec]

Bottom PCIE slot. Putting it in the top one was the mistake I made the first time around.

I'll try switching things around.

The image of the board that inachu posted is the correct one.

- edit - I've tried all the combinations possible with the PCIE slots except one (having the card in the blue 16x slot but without the VGA switch card), apart from achieving a 4x link speed twice, no luck I'm afraid.

Right now it's back to the 'normal' configuration (card in blue 16x slot and VGA switch in the grey one) along with a CMOS reset (8x link speed still).

 

[Burpo]

Try HWINFO instead of CPU-Z & see what it says..

http://www.hwinfo.com/download.php

 

[Ketchup]

A 750 wouldn't even saturate the bus of an 8x, so while disappointing, it's not really holding you back imo.

 

[inachu]

Wondering if down revving the cmos might fix the issue but is usually not good advice.

 

[mikeymikec]

I did a CMOS reset (jumper switch). I also downgraded the BIOS to a version that I know that I had a 16x link speed at least with the previous graphics card.

@ ketchup79

Are you referring to PCIE 2.0 8x when you made that statement, and is there some way I can test PCIE bandwidth usage?

@ Burpo

HWINFO32 reports:
PCIe v2.0 x16 (5.0 Gb/s) @ x8 (2.5 Gb/s)