PCIe - x16 versus x4

[PhilipM]

Hi,

Due to a space issue on my new rig, I have the graphcs card (4870) in an x4 mode slot, rather than an x16 slot. Will this make much difference to the performance?

Thanks,

 

[dmxdex2020]

I would image it would make a a lot of difference being in the 4x slot. a lot of peformance drop.

 

[RavenXXX2]

X4 is to slow even on PCI-E 2 mobo's.

 

[cmndr_andi]

If this test is to be believed, it shouldn't be too bad.

 

[S_D]

If this test is to be believed, it shouldn't be too bad.

That keeps getting quoted, but I don't think it's a fair test. It only demonstrates single GPU, CPU-->GPU data flow, and not inter-GPU traffic that you'd get in a Crossfire situation. I'm not fully conversant with the Crossfire ribbon's role, but I'd be wary to argue that no traffic goes over the PCI-E bus in Crossfire. I'd like to see a true Crossfire test to be sure of the implications of a x4 (or otherwise) slot.

 

[cmndr_andi]

That keeps getting quoted, but I don't think it's a fair test. It only demonstrates single GPU, CPU-->GPU data flow, and not inter-GPU traffic that you'd get in a Crossfire situation. I'm not fully conversant with the Crossfire ribbon's role, but I'd be wary to argue that no traffic goes over the PCI-E bus in Crossfire. I'd like to see a true Crossfire test to be sure of the implications of a x4 (or otherwise) slot.

Aye, but I was under the impression that the OP was only trying to connect his primary GPU via a x4 socket. In this case, the test would be valid. But I do agree with your scepticism when using this test to justify lower speed sockets used for multi-GPU configurations.

 

[PhilipM]

That's right. My initial thought was that x4 would be rubbish compared to x16, but then the crossfire thing got me thinking as to why these sockets were not both x16.

A performance drop of 5% is pretty good considering. I'm sure I'll fix it once I've researched the best wifi PCI card to get (fitting the 4870 in the x16 slot, blocks the pcie x1 slot I'm using for the current wifi card). However, in the mean time, I can live with the smallish hit. Many thanks.

 

[HazardO]

My advice would be try it for your self. Choose the games you care about and benchmark them on your system.

 

[ArtificialFoxx]

If it is a pci-e 2.0 slot then I don't think you'll have problems with that card

 

[S_D]

Aye, but I was under the impression that the OP was only trying to connect his primary GPU via a x4 socket. In this case, the test would be valid. But I do agree with your scepticism when using this test to justify lower speed sockets used for multi-GPU configurations.

Yes, of course, you're right. I'm just blind that I missed the OP's situation!

 

[sckam]

Why don't you buy a usb wifi adaptor and use it instead of the wifi card and put the 4870 in the faster slot