Radeon HD7900

gbtg · Dec 24, 2015

hi,

using CPU-Z and GPU-Z i found that my radeon hd 7900 runs at pci-e 4x v2.0 but supports pci-e 16x 3.0.
my motherboard is a ASRock H77 Pro4-M.

i tried putting the card in another slot which resulted in it in running only at pci-e 1x, so i switched it back.
i tried putting the card under a lot of load to see if it was a throttling issue but it did not change anything.

any help would be much appreciated.
if you need further system infos let me know.

Masterchiefxx17 · Dec 26, 2015

Hi and Welcome!

Your graphics card will only support a PCIe 3.0 x 16 card in the first PCI slot. The others will not result in the highest speeds.

Where are you seeing that your card is not running at its best performance when connected in the top PCI slot?

Cworange · Mar 18, 2016

You can also check in the PCI subsystem of your BIOS. Some of those slightly older boards auto-set the PCI to auto detect, and if the GPU BIOS and motherboard BIOS are not updated to a certain version sometimes you get the lack of PCIe 3.0 detection (properly). You may be able to manually toggle PCIe 3.0 (Gen3) in the bios to circumvent that. However there is nothing to worry about because even today the PCie 2.0 speeds are not fully saturated. There is like a .005 speed drop from PCie 3.0 to PCIe 2.0 under the most demanding situations even regarding gaming.

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Radeon HD7900

gbtg

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Masterchiefxx17

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Cworange

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