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Need info about PCIe

Bobek289
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PCIe 3.0 cards/slots are backwards compatible with PCIe 2.0. 

 

If I connect PCIe 3.0 16x graphic card to 2.0 16x slot, is it going to work on 3.0 8x?

 

A PCIe 3.0 16x card in a PCIe 2.0 16x slot will work @PCIe 2.0 16x. The bandwidth of PCIe 2.0 16x is almost the same as the bandwidth of PCIe 3.0 8x.

 

If so, how are 2 graphics 3.0 gonna work (4x/4x ?) in crossfire on 2.0 mobo that work on 8x/8x in crossfire?

 

Two PCIe 3.0 16x cards that are each inserted in PCIe 2.0 8x slots will work @PCIe 2.0 8x. Again, bandwidth of a PCIe 2.0 8x is almost the same as the bandwidth of PCIe 3.0 4x.

Posted

I dont know if this is the right place to put question, if it is not please move it where it belongs.

 

If I connect PCIe 3.0 16x graphic card to 2.0 16x slot, is it going to work on 3.0 8x?

If so, how are 2 graphics 3.0 gonna work (4x/4x ?) in crossfire on 2.0 mobo that work on 8x/8x in crossfire?

 

e.g. this mobo and graphics

 

http://www.gigabyte.us/products/product-page.aspx?pid=3901#sp

 

http://www.asus.com/Graphics_Cards/R72601GD5/

 

Thank you in advance!

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Posted

PCIe 3.0 cards work on PCIe 2.0 slots.

PCIe 3.0 is twice the bandwidth of PCIe 2.0.

PCIe 3.0 8x slots are as fast as PCIe 2.0 16x slots.

GPU's lose zero performance on PCIe 2.0 8x slots so if you run a card in a PCIe 3.0 4x slot you'll still get the same performance.

 

That help?

.

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I dont quite understand last sentence, but i already knew the rest. What i want to know is, if in crossfire PCIe 16x work on 8X, does 3.0 16x graphic card works on 8x or 4x?

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I dont quite understand last sentence, but i already knew the rest. What i want to know is, if in crossfire PCIe 16x work on 8X, does 3.0 16x graphic card works on 8x or 4x?

 

What he's saying is that PCIe 3.0 4x (which is equal to PCIe 2.0 8x) has more bandwidth than the GPU needs. You will not see any issues or slowdowns from using these slots vs 3.0 16x slots 

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PCIe 3.0 cards/slots are backwards compatible with PCIe 2.0. 

 

If I connect PCIe 3.0 16x graphic card to 2.0 16x slot, is it going to work on 3.0 8x?

 

A PCIe 3.0 16x card in a PCIe 2.0 16x slot will work @PCIe 2.0 16x. The bandwidth of PCIe 2.0 16x is almost the same as the bandwidth of PCIe 3.0 8x.

 

If so, how are 2 graphics 3.0 gonna work (4x/4x ?) in crossfire on 2.0 mobo that work on 8x/8x in crossfire?

 

Two PCIe 3.0 16x cards that are each inserted in PCIe 2.0 8x slots will work @PCIe 2.0 8x. Again, bandwidth of a PCIe 2.0 8x is almost the same as the bandwidth of PCIe 3.0 4x.

There are more things in heaven and earth then are dreamt of in your philosophy.

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Posted

I know you said crossfire, but just a point to remember,
AMD cards can use 4x slots (whether 2.0 or 3.0) while Nvidia cards require 8x slots (whether 2.0 or 3.0)

Case: Lian Li PC011-D - CPU: 3900x - GPU: 2080ti Reference - Mobo: Gigabyte - Ram: Corsair 4x16gb 3200MHz - SSD: 2TB Samsung Evo NVME

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In the meantime i figured it out by myself, but thank you all for your time :)

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