PCIe speeds not right

[Darkbreeze]

Crazy question. I just realized this after a few weeks of using this new build. CPU-z is reporting my PCIe link speed for the GPU is only x8 when it should be x16. The Sapphire R7 240 card is PCIe 3.0 with x16 structure. The sabertooth 990fx r2.0 board has multiple x16 structure and I'm parked in the correct slot so it SHOULD be running at x16 speed but it's not. I can't find any settings for this in the BIOS and I've pretty much always seen this auto negotiate to the correct speed on other cards and boards. Anybody have any idea why it's not running at the correct speed or where to change the settings. Could a setting be blocking it from achieving the right speed? I realize the board is only PCIe 2.0 but it should still run at 2.0 x16. Thanks.

FX-8320 (@4.3ghz)
Sabertooth 990fx r2.0
Sapphire R7 240
16GB DDR3 1866mhz
Seasonic 620w PSU

 

[VincentP]

PCI-E 3.0 x8 speed is exactly the same as PCI-E 2.0 x16 speed.
The R7 240 won't go even close to saturating the bandwidth of a PCI-E 3.0 x4 link.

 

[i7Baby]

Yep your mobo spec - http://www.asus.com/Motherboards/SABERTOOTH_990FX_R20/specifications/- says "3 x PCIe 2.0 x16 (dual x16 or x16/x8/x8)"

So I gather you don't have it in the pcie slot nearest the cpu.

Or you've chnaged it eg http://www.ehow.com/how_8758532_change-pcie-speed.html

 

[Darkbreeze]

Ok, but since the board controls the link speed, and the board has 2.0 structure, shouldn't it be reporting as x16@PCIe 2.0 instead of the other way around. And if not then why is CPU-Z reporting the max supported link speed as x8. Max supported should be reading as x16 regardless of whether it's going off the board or the card as they both support x16 speeds for 2.0 and 3.0 respectively. You may be right, I'm just trying to understand why it's being reported as half speed.

 

[i7Baby]

Maybe GPU-Z would be more appropriate.

 

[Darkbreeze]

It's in the top x16 slot. I've done this once or twice. Heh. And there is NO PCIe frequency control or timing or any other settings for the PCI speed that I can find anywhere. The only setting at ALL I can find anywhere in the BIOS is the PCIe spread spectrum and that's only got enabled or disabled. Nothing else unless it's going off the voltage from something else entirely.

 

[i7Baby]

Well then I think you're saying the CPU-Z reading is wrong.

 

[VincentP]

As I commented above, it really doesn't matter.
To start to see any difference between PCI-E 3.0 x8 or x16 speed you would have to have at least a GTX 760.

 

[Darkbreeze]

GPU-Z reports the same as seen here. And Vincent, it's not so much the speed I'm concerned about, especially with this POS card. But I'm ordering another GPU card and if there is going to be an issue with link speed I don't want to spend money on a card that's going to fail to perform properly so I'd like to know things are reporting accurately or at least know why they're not. And it is the 3.0 speed that's being reported at x8 so at least I know it's actually x16 2.0 but it still doesn't explain why the max supported was showing the same rather than x16.

 

[i7Baby]

I suppose then to make sure, buy another motherboard.

 

[VincentP]

Anyone using SLI or Crossfire on a decent motherboard with a LGA 1155 or 1150 CPU is relying on PCI-E 3.0 x8 per card.
Benchmarks consistently show it makes very little difference.
Don't stress about it. Buy your new card.

 

[Darkbreeze]

You know, after looking at the GPU-Z summary again I'm wondering why the bus interface is showing x8 1.1 instead of x8 2.0 since the slot is a 2.0 slot and the card is a 3.0 card?

 

[Darkbreeze]

Nevermind. After initiating the render test it changed to 2.0. Stupid.