Crossfire 7950 issue with dual monitor.

[Phobiarg]

System Specs:

FX 8320 @ 4.4 ghz

8GB DDR3 RAM @ 2132 mhz

Gigabyte GA-990FXA-UD3

Gigabyte Radeon HD 7950 

MSI Radeon HD 7950

Seasonic SSR-750RM 750W PSU

 

I just purchased a second 7950 to increase the lifespan of my aging gaming pc. This is my first time ever running dual GPUs and knew there were some issues with it. But I have run into a rather bizarre issue that I can not seem to find any information online about it. I attempt to run some benchmarks to see how much more performance I was getting. My standard benchmark has always been Metro Last Light. I loaded it up only to have the screen flickering and having what looks like a sync issue. I am running dual monitors, this is the weird part.

 

I thought maybe the second hand 7950 I purchased was bad, so I turned crossfire off and it works fine. I turn crossfire back on, issue returns.

 

I then tried to disable ULPS. Didn't fix the problem.

 

I then tried to underclock the cards from 960mhz to 900mhz. No dice, same issue.

 

Finally I decided to disable one monitor. Perfect, no issue, runs great. Ended up getting 58.6 fps.

 

I have tried everything I can think of to fix the issue short of getting rid of a monitor (not gunna happen lol)

 

Another thing I noticed, when I finally got a good benchmark I got 58.6 fps, but my single 7950 running a modest overclock (1130/1800) got a 57.33. Not sure why, but shouldn't I be getting more than 1.3 fps more with a second video card even though both are running at 960/1250?

[Guest]

Tried reinstalling drivers?

[Phobiarg]

Installed beta drivers, flickering issue resolved, overclocked to 1100/1575 on both cards, performance issue resolved. Thanks for the help!

[SkilledRebuilds]

Installed beta drivers, flickering issue resolved, overclocked to 1100/1575 on both cards, performance issue resolved. Thanks for the help!

If you can quickly state which drivers you came from, and which ones you have now.

(Even tho it probably a bug, and not a real driver issue, never know, and future ppl who read this can see which)

[Phobiarg]

I went from 14.9 to 14.9.1, my clocks went from 960/1250 @ 1093mV to 1100/1575 @ 1188mV on both cards. I used MSI Afterburner with default limits to achieve these clocks. I didn't feel I needed any more of an overclock at this time but my Gigabyte 7950 got a stable 1135/1800 @ 1200mV when I was running single card.

 

I also flipped the cards, my MSI card is now on the bottom and the Gigabyte card is on the top. The reason I decided to flip the cards was the MSI vents to the front and back, the Gigabyte card vents from the sides. I think the Gigabyte venting from the sides was allowing more exhaust heat to end up getting sucked into the MSI. My temps went from 72C MSI/61C Gigabyte to 64C MSI/67C Gigabyte. CPU temps also increased by adding the second card, CPU went from 54C to 58C with a Coolermaster 212 Evo.