Interesting discovery regarding Dual GPU CrossfireX Setting

[ahav92]

Hi everyone

 

I would like to discuss about a very interesting yet frustrating discovery that I made regarding running skyrim with Dual GPU cards like HD 6990

 

I have been playing Skyrim with HD6990 for a long time and two things made the game almost unplayable and very irritating

 

The first problem is the infamous microstutter issue. When you are close to the wall or in dungeon or interior, your frame rate stays in 60 but your screen gets extremely jittery. It is still playable but it is extremely annoying. When you move to 3rd person, the microstutter disappears.

 

The second problem is the very weird stutter issue and as far as I can describe this correctly, I think it is very similar to "Skipping Frame" issue.

When I first load the game, say continue from my last save, the game runs as smoothly as butter (60fps) regardless of indoor or outdoor.

 

But after you load several other regions (Loading from Whiterun -> Skyrim or Skyrim -> certain dungeon....etc) or any loading that accompanies black loading screen with white steam and gaming tips, it starts to stutter so badly that it is almost unplayable.

As soon as I load certain new area (It is not about loading objects while you are in outdoors) the framerate starts to get cut off, as if the game pauses for like a millisecond and resumes.

 

So the frame rate starts at 60fps as usual and then few seconds later, it drops to 0fps for like 0.01sec, and then comes back to 60. And this happens like every 5 seconds or so and sometime worse, and make the game almost unplayable. In summary, the frame rate gets extremely discontinuous.

 

I can also notice from the sound from my HD 6990. When everything is running normal, the sound from the GPU is continuous and stable. But as soon as that stutter starts to happen, the sound is discontinuous and gets cut off, just like the game screen.

 

This was so frustrating that I spent my last 2 days trying to figure out what was causing this issue

And I found out that it has to do with CrossfireX setting. Believe or not, the microstuttering issue has been almost resolved at ATI Cataylst 13.2 Beta drivers. You can check this link for detail review. http://benchmark3d.com/microstutter-case-study-skyrim-exam-day

 

But the second problem, the discontinuous framerate remains unresolved. So with 13.2 Beta 4 driver installed, I switched CrossfireX mode from Default to Alternate Frame Rendering, aka AFR Friendly Mode.

 

This solved the discontinuous framerate issue completely. It kinda makes sense since AFR mode distributes even frame and odd frame to each GPU chip, thereby making the whole process more efficient. But guess what, microstutter came back as I switched to AFR mode!!

 

The other problem with AFR mode was that whenever I press ESC to save to game or look at the journal, the screen gets very bad flicker. Also, my character face flickers really badly, though all the other character's face looks totally fine.

 

So in summary, switching to AFR Friendly Mode does resolve the discontinuous frame rate, but it accompanies microstutter and screen flickering when you press ESC and on your character's face

 

Staying in Default CrossfireX setting resolves the Microstutter issue and you don't get flickering screen but after several loading screens, but you get severe framerate discontinuity, making the game almost impossible to play.

 

So it is one way or the other but I don't know why ATI can resolve these two issues at the same time. I thank them for resolving the Microstutter issue but discontinuous framerate is as bad as microstutter or even worse sometime.

 

Is there anyone who resolved these two issues at the same time? Or can anyone explain in detail why switching to AFR Friendly Mode removes the discontinuous framerate?

 

Thank you for reading such a long report, but I thought we could share some ideas regarding running skyrim under Dual GPU or Crossfire settings

 

Cheers

Edited April 4, 2013 by ahav92

[Valkyrie]

Looks like ya really did a lot of research there. Cheers! My honest opinion would be to post that in the pertaining forum section over at Guru3d.com. There are some very knowledgeable ppl here but the odds are most who see this thread will be more or less pros on Skyrim not advanced 3d settings. Over at Guru3d there is a bunch of unbelieveable educated ppl in the fine arts of videocard inner workings. If they can't help you or at least explain why this is happening I would be very surprised. Good luck!

 

http://forums.guru3d.com/

[ahav92]

Thank you so much for valuable information!

 

It is unbelievable that such problem can sometime lead you to in-depth understanding of such mechanism

 

I will make sure to post this on guru3d as well. Hopefully they can help me out to understand this issue more thoroughly

 

Thanks again and cheers!

Edited April 4, 2013 by ahav92

[ahav92]

Looks like ya really did a lot of research there. Cheers! My honest opinion would be to post that in the pertaining forum section over at Guru3d.com. There are some very knowledgeable ppl here but the odds are most who see this thread will be more or less pros on Skyrim not advanced 3d settings. Over at Guru3d there is a bunch of unbelieveable educated ppl in the fine arts of videocard inner workings. If they can't help you or at least explain why this is happening I would be very surprised. Good luck!

 

http://forums.guru3d.com/

 

Thank you so much for valuable information!

 

It is unbelievable that such problem can sometime lead you to in-depth understanding of such mechanism

 

I will make sure to post this on guru3d as well. Hopefully they can help me out to understand this issue more thoroughly

 

Thanks again and cheers!

[Astin8]

Thank you!!!! You have answered my questioned that i have had for agggggggggggggggges!

I was having the exact same problem with micro stuttering while in crossfire mode and it gets dam annoying.

My rig which is an i5 2500k oc'd at 4.5GHz and cross fired 6850's and i was starting to think my pc struggled to run Skyrim.

I would turn off crossfire completely and Skyrim would run fine on High settings but as soon as i turn it on MICRO STUTTERING!!!!!!!!!!

I just tried AFR mode for Skyrim setting it in a 3d application and it as fixed it with quite a nice boost in performance. I also have overclocked cards which are running at 870mhz and ram is at 1160mhz.

Although i get the silly pause menu flickering now its better than it use to be!

Any idea how to fix the pause menu flickering?

 

Thanks again :)