Crossfire + multiple monitors + DX9 = broken vsync

[mariyoshikong]

Original Post: I have been gaming on my 3008wfp for over a year now and recently decided to pick up a 2408wfp for a second monitor. I decided to try a few games on the 24'' just to see how it handled them, and noticed that the frame rate seemed very jerky. I decided to try with crossfire disabled, and lo and behold the stutter was gone. The strange thing is that I have never noticed this phenomenon before on my 30''. FWIW, the game that suffered the most was Mass Effect 2. I am curious if anyone knows why it would show up on the 24'' but not the 30''.

Update 12/29/2011: The stuttering that is described in the original post above is a symptom of broken vsync. This issue is caused by the following conditions:

a) using crossfire
and
b) using an extended monitor
or
c) using eyefinity
and
d) while playing DX9 titles

A solution for the abd combination can be found in post #12 (thanks Hevy!). I am still trying to find a fix for the acd combination.


My setup is the following:
Intel Core i7 3930k@ 4.4 Ghz
ASUS P9X79 Pro
6990 + 6970 in crossfire
Gskill 32GB @ 1600:9 9 9 27
Catalyst 12.1 preview
Catalayst 11.11 cap 3

 

[BFG10K]

I’m guessing you ran games at different resolutions on the displays? That could have an impact.

 

[mariyoshikong]

You are correct. I ran them both at native. FRAPS was showing 60-62 rock solid on both displays in Mass Effect, but the 24'' was noticeably jerky. I even turned FRAPS off just to make sure that wasn't screwing something up.

 

[DirkGently1]

I suspect that to really get to the bottom of this you would have to start with a clean install of Windows using one monitor each time.

 

[mariyoshikong]

Actually, I played around with it some more last night and it looks like I forgot to include a crucial detail. When I was initially testing, I had both monitors running simultaneously and was just changing the primary. When I disconnected the 30'' and just played on the 24'' everything became smooth. I went back to having both connected, and it was jerky again (on the 24'' only). I disabled crossfire with both connected, and it was smooth again.

So it appears that having the 30'' as a secondary in addition to using crossfire is what is causing my issue. Has anyone else experienced this before?

 

[cmdrdredd]

Does changing the connection type affect anything? Like using HDMI or display port instead of DVI or vise versa?

 

[mariyoshikong]

I tried it with different connectors at first, Displayport on the 24'' and DVI on the 30''. But then I switched to DVI on both and still had the problem.

 

[cmdrdredd]

Just wondering because I've seen issues with eyefinity and using certain connections to the monitor helped, didn't know if it were somehow related a bit.

 

[mariyoshikong]

After searching around the web, I have a new theory that I am going to test out tonight. I have found a few threads that seem to indicate that V-sync is being disabled while running an extended display and crossfire. It also turns out that Mass Effect 2 is frame capped at 62 so I wouldn't know if V-sync was turned off by just looking at FRAPS. I will check some other games when I get home and see if V-sync is indeed being disabled.

 

[mariyoshikong]

Just an update on my issue. It looks like I am definitely losing v-sync with crossfire enabled and a second monitor attached, but only in DX9 games! I am getting the same bug as a few other people have reported where enabling a second monitor with crossfire causes the frame rate to be capped at 120 instead of 60. As far as I can tell there is no fix for this bug (most of the posts I found were nearly a year old). If I stumble upon a fix I will post it here.

 

[mariyoshikong]

One more thing. I picked up 2 additional Dell 24'' monitor to play around with eyefinity, and can confirm that this bug also shows up while using eyefinity. This might explain the large number of reports of crossfire performing like crap with eyefinity.

 

[Hevy187]

To fix your issue, you must have windows identify your main display monitor as number one (1) in both Windows display properties (Screen resolution in windows 7) and in CCC display properties.
If in windows your main display is identified as 2, then you simply swap the DVI connectors on your graphics cards. DO THIS FIRST.
Thn in CCC if your main display is numbered 1, leave it and your problem is fixed, if not right click the display and click "swap", now your main display should show as (1).
If your start taskbar has moved to the extended display, simply go back to windows screen resolution, and click your main display (1) then check the box which says "make this my main display" This will resolve the problem you are stating.
All in all, you just need to remember that WINDOWS and CCC need to identify your main display as 1.
This should help alot of people!

 

[mariyoshikong]

Sorry for the really late reply on this one. I tested your fix and it works great when using the additional monitors in extended desktop mode. I am still having trouble with eyefinity +crossfire though. Windows sees the entire array as display #1 and CCC shows all three. Have you tried fixing this problem with eyefinity + crossfire?

 

[Pulsar]

Your problem statement seems fairly vague, so I'll simply say this:

If you see screen tearing on 1 or 2 of your LCD's using eyefinity, this is normal. There is an acknowledged hardware issue using two types of outputs (mixing dvi and displayport) that results from a difference in the internal timing that causes screen tearing. This IS NOT fixable, unless you purchase another $100 active display port HUB that will run all your eyefinity displays from the display port output.

You can notice this tearing in windows by dragging open windows around the screens. Do a search for 'eyefinity screen tearing" on youtube to find multiple examples.

 

[mariyoshikong]

Your problem statement seems fairly vague, so I'll simply say this:

Sorry about that, let me clearly state the issue I am having.

When using eyefinity with crossfire and running any DX9 title I cannot get vsync to work properly. There is tearing (not due to mixing dvi and displayport) and the frame rate is capped at 120 (2 GPUs) or 168 (3 GPUs). Eliminating any of the above criteria results in perfectly working vsync.

If you see screen tearing on 1 or 2 of your LCD's using eyefinity, this is normal. There is an acknowledged hardware issue using two types of outputs (mixing dvi and displayport) that results from a difference in the internal timing that causes screen tearing. This IS NOT fixable, unless you purchase another $100 active display port HUB that will run all your eyefinity displays from the display port output.

You can notice this tearing in windows by dragging open windows around the screens. Do a search for 'eyefinity screen tearing" on youtube to find multiple examples.

I am aware of this issue, but it is not related to the problem I am having. My setup has changed since I originally started this thread, and I now have a 6990 crossfired with a 6970. All three monitors are connected via displayport to the 6990.