6870 crossfire with PCI-E X4

[Skurge]

Mass effect 2, Left 4 Dead 2, StarCraft 2 if you can.

Are any SC2 replays you can recommend so I can bench them? Non of my games are intense enough to be good benches.

 

[Smartazz]

Skurge, once you have both cards installed could you go into GPU-Z and tell me what speed your second PCI-e slot is running? I know it's an odd request, but my 4x slot was indicated as PCI-E generation 1 and I want to know if GPU-Z is accurate.

 

[Smartazz]

I'm about to pull the trigger on a second 6870 so I'll put up some benchmarks with my CPU.

Edit: OP, take a look at this benchmark: http://www.techpowerup.com/reviews/AMD/HD_5870_PCI-Express_Scaling/7.html

I'm confident that the 4x slot won't slow us down very much.

 

[Skurge]

I got everything set up and GPU-Z shows the 2nd card as PCI-E 2.0 4X.

But now after a few mins of load it sounds like the top card shuts down and the display goes black. I set the Fans to 100% and the top card doesn't exceed 60 degrees. I know both cards work individually and the PSU can support both cards and isn't faulty cause I tried it with Dual 5870s at work and I tried another PSU with my cards and I have the same issue.

 

[Bman123]

That sucks I really wanted to see some results

 

[Smartazz]

Have you tried switching the cards?

 

[Skurge]

Have you tried switching the cards?

Yep, I tried them on a different board as well. Seems like I'm not the only one with the issue. There are a few people who have that issue, but it seems like it only happens with the gigabyte cards.

For the short time they did work, I was getting great performance, didn't notice any microstutter.

I tried a bios update for the cards, but they had the newest bios on them, I tried flashing them with ASUS bios and I still have the issue. I have no idea what to try now.

 

[Smartazz]

Sorry to hear that, but it's good that you didn't notice any microstutter.

 

[Skurge]

I won't be able to put any benchmarks now. Looks like I'm going to trade in the cards for a 7950 at the end of the month. I can't figure out whats wrong.

I was able to complete one bench though. Scaling was really good.

It shows no multiGPU, I disabled it so I could play some games after the bench.

 

[Smartazz]

Bummer, at least you'll get a 7950 which looks to be a very good card that won't suffer from VRAM limitations.

 

[Elcs]

Thanks for this thread. I have an x16/x4 board and an HD6870... was wondering what Crossfire would be like somewhere down the line and this has been very useful.

 

[Zanovar]

cheers for that skurge,although not my cup of tea i still like reading about it.:thumbsup:

 

[FlanK3r]

Nice one! Im looking forward at Crossfirewith PCIe x4 speed. How will be limited or not.