if i crossfire two Sapphire r9 380x in pci express 2.0 x16. Will there be any performance lagging & disadvantage ?

[Galib 360]

Hi,
What will happen if i crossfire two r9 380x in pci express 2.0 x16. I mean will there be any performance lagging & or any disadvantages?

My motherboard is asrock b85 fatality killer.One thing about my motherboard is it has one pci ex-2.0 x16 and one pci ex-3.0 x16. Is there any disadvantages or difficulty i would face while crossing between pci ex-2.0 x-16 and pci ex-3.0 x16?

Thank you.

 

[Rogue Leader]

There is a very minor (like 1%) difference in performance, you effectively would never notice it. Nothing to worry about.

 

[william p]

The R9-380 if it's like my R9-285 doesn't have the Crossfire bridge connector. The PCIe 2.0 isn't a problem in itself. The connector was removed from the PCIe 3.0 cards because the 3.0 bus could handle the extra data. I was told in the forums at Overclock.net (Tonga GPU club) that it wasn't a problem. I don't know if that means it works OK but slower, or if there's no difference. I didn't see any performance numbers to back up the claim. I own 2 R9-285 ITX cards but they won't Crossfire due to being too thick for good cooling, so I can't tell you myself. I would ask around some more first.
I guess the real question is how does Crossfire perform on PCIe 2.0 without the bridge connector. I'm sure somebody knows, but I don't know who.
I would try asking AMD support. They must have tested this.

 

[Rogue Leader]

The R9-380 if it's like my R9-285 doesn't have the Crossfire bridge connector. The PCIe 2.0 isn't a problem in itself. The connector was removed from the PCIe 3.0 cards because the 3.0 bus could handle the extra data. I was told in the forums at Overclock.net (Tonga GPU club) that it wasn't a problem. I don't know if that means it works OK but slower, or if there's no difference. I didn't see any performance numbers to back up the claim. I own 2 R9-285 ITX cards but they won't Crossfire due to being too thick for good cooling, so I can't tell you myself. I would ask around some more first.
I guess the real question is how does Crossfire perform on PCIe 2.0 without the bridge connector. I'm sure somebody knows, but I don't know who.
I would try asking AMD support. They must have tested this.

The removal of the connector has nothing to do with PCIe 3.0 vs 2.0 and it will work fine on his board. All Current AMD Boards are only PCIe 2.0 if it didn't work you could never crossfire on them.

As for the performance difference, as I said, its very small this has been tested by many different outlets and its only a couple percentage points.

 

[Galib 360]

so... instead of crossfiring in PCI ex 3.0 x16 if i crossfire two R9 380x in PCI ex 2.0 x16 ,there will be minor (like 1%)difference in performance, right?????

 

[Rogue Leader]

so... instead of crossfiring in PCI ex 3.0 x16 if i crossfire two R9 380x in PCI ex 2.0 x16 ,there will be minor (like 1%)difference in performance, right?????

Correct its a couple percentage points tops. There have been multiple tests of this, here is a good quick look you can see the tiny difference 2.0 and 3.0 make:

http://www.guru3d.com/articles_pages/pci_express_scaling_game_performance_analysis_review,10.html

And here using SLI (same as crossfire)

http://www.guru3d.com/articles_pages/pci_express_scaling_game_performance_analysis_review,16.html

 

[william p]

I guess you answered my question too. Thanks.

 

[Galib 360]

thanks rogue leader
for not only solving ny problem but also the problem of will p.

you're a great contributor to Tom's hardware.