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5870 Crossfire weirdness

SystemSystem Member, NoReporting Posts: 178,019 Arc User
edited September 2010 in Graphical and Sound Issues
I've Googled and searched the forums for this issue, but have yet to find anyone mention this 'fix'...

I run STO @ 1900x1200 with all settings maxed, with SSAA enabled in the CCC. 2 X HD5870 1GB crossfire, 10.8 drivers, Core i7, 6GB RAM.

Most of the time, I get a solid 60fps, but then performance will degrade, especially on away team missions. Frame rate drops, and I get a sort of stuttering.

I know I've read about this issue, and have turned off dynamic lighting to avoid the freezes and crashes on away team missions.

But here is the weird thing:

When performance drops off, I've discovered that disabling and reenabling vsync will often correct the problem. Back to a rock solid 60 fps.

Why would a simple thing like that temporarily but completely correct the problem? It's almost as if crossfire has trouble keeping each GPU in sync in order to maintain display vsync.

Has anyone else experienced this problem and subsequent fix?
Post edited by Unknown User on

Comments

  • Archived PostArchived Post Member Posts: 2,264,498 Arc User
    edited September 2010
    Rai,

    I found that if I toggle the post-processing, it "fixes" it but then the AA appears to drop completely if not mostly.

    Is your AA the same?
  • Archived PostArchived Post Member Posts: 2,264,498 Arc User
    edited September 2010
    Doc

    No I haven't found that toggling post processing fixes it, only vsync. I havent noticed it affecting AA either. Turning off PP certainly improves performance temporarily (looks terrible tho), but then the FPS eventually begins to suffer again.

    This is definitely a cummulative thing. It almost acts like insufficient VRAM for the textures being used...I guess that is possible? Both of my 5870s are 1GB, and perhaps that's just not enough for STO max textures and 1900x1200 8XSSAA? Although, I have found that disabling SSAA still doesn't prevent the inevitable degradation in performance. It seems the only way to avoid it completely is disable catalyst AI (disable crossfire), but I just refuse to do that. :)

    Perhaps toggling vsync force-flushes the cached textures from VRAM and explains the temporary 'fix'?
  • Archived PostArchived Post Member Posts: 2,264,498 Arc User
    edited September 2010
    I noticed this recently in my 5870 Crossfires.

    Not sure what changed but it does "feel" like the video memory needs flushed every so often. A reboot fixes the issue.

    If you have a LCD that supports 120hz turn off Vsync and type /maxfps 120

    That will allow the framerate to exceed 60fps and you don't really see any tearing at 120hz.


    Battlefield Bad Company 2 is a real nightmare to work with compared to STO. DX9 doesn't even work properly with ATI cards in BFBC2.
  • Archived PostArchived Post Member Posts: 2,264,498 Arc User
    edited September 2010
    I have a similar setup of 2 5850s in crossfire and an 4GHZ over clocked i5, with 8GBs of ram. I recently upgraded from from windows vista to windows 7 and I have seen a performance drop off as well. But I to have noticed if I toggle the post processing check box it will get my FPS back to 60+. Is this game known to bleed graphics ram? I noticed games like dragon age has a memory bleed that will need to be "flushed" every once and a while (Vsync toggle flushes GRAM).
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