Hi T M,
AMD CrossFire will only work when games are run in Full Screen Mode. It's always recommended to run in Full Screen Mode to get the best performance and the smoothest gameplay. The Graphics Cards you are using do not have access to AMD's Frame Pacing Technology, as such you may experience Micro Stutter on occasion. This can sometimes be mitigated by using Vsync and an FPS Cap to lock the FPS slightly below your average FPS. By doing this, if you can stay above your set FPS cap in most instances you should have a smoother gameplay experience. In order to set an FPS cap for games you will need to use an application such as MSI Afterburner.
In order to improve your temperatures i would recommend to increase the maximum fan speed to 100% within AMD Catalyst Control Center > Overdrive in order to bring the hottest GPU temp down. In addition, i would recommend removing the side panel of your case if you can in order to allow the heat from both Graphics Cards to dissipate more effectively. Furthermore, you may wish to remove any spare PCI brackets from the rear of the case, and install some High Static Pressure Fans to the front of your case in order to force cold air between the two Graphics Cards.
I would recommend updating your Graphics Drivers to the latest available from our website.
Step 1> Go to http://support.amd.com/en-us/download
Step 2> Scroll down to manually select your driver
Step 3> Select Desktop Graphics
Step 4> Select Your Graphics Card Family from the list (Radeon HD Series)
Step 5> Select Your Specific Graphics Card (HD 5xxx)
Step 6> Select your Operating System (Win 10)
Step 7> Click Display results
Step 8> Download Catalyst 15.7.1 Drivers
Please install our Graphics Drivers following this guide. http://support.amd.com/en-us/kb-articles/Pages/catalyst-windows-install.aspx
I'm on 15.7.1 /beta drivers (also done the past few versions aswell). My fans are always maxed out and actually have my case open due to me constantly fiddling with the cards in different spots and whatnot after new drivers.
Idle temp is normal, single card under 90%+ load Im at 50-60c which is normal. I only included the heating issue because I thought it somehow would correlate to the problem of reduced performance in crossfire not because I found it alarming or detrimental to anything else.
What else should I try? I've reseated them, reordered them, ran only the card in the second slot to rule out faulty card, tried different 6pin connectors, reordered crossfire bridges, tried each bridge separate, underclocked/overclocked, different drivers. I just cant get crossfire to work like it should.
What makes you think CrossFire is not working as it should? How is game performance? Are you seeing an FPS increase?
Can you provide some examples and some data, perhaps some benchmarks of 1 GPU vs 2 GPU. Unigine Heaven would be a good place to start for benchmarks.
I get more fps but worse performance, lots of stuttering/hitching.
Heres Unigine Heaven and GTAV benchmarks. Right picture in each set is crossfire.
Same case with Rocket League, CS:GO, Call Of Duty 4, Mad Max, Killing Floor 2, Dirt 3 Complete Edition.
Is there anything else we can try? I just want to articulate this problem to you in full so I can at least get some closure. I've had these 5770's since 2009ish (half a decade!!!) full use and they havent quit on me once this would be the first time I've ever really had a problem.
bump- seems to be frame latency problem i guess thats on your guys end.