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Chaniyth

Member

Registered: 2008-03-10

Posts: 33

SLI enabled drops frames per second by half... any suggestions?

Greetings,

I've been a linux user since 1998, and been Linux exclusive since 2006.

Ok, so for several months now i've had an SLI setup... dual GeForce GTX 550 Ti cards, both from same manufacture and are identical. I've been using SLI mode, however I have discovered that my framerates are HALF of what they are if only a single card is used[i.e. 120fps in single card mode equals 60 - 64fps in SLI... vsync is disabled as well]! Seriously, WTF? It doesn't matter if I set it to Auto, AFR, or SFR [SFR gives worse performance], I get half the frame rates, but with it OFF I get full frame rates.

Here is my xorg.conf...

# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig:  version 295.20  (buildmeister@swio-display-x86-rhel47-05.nvidia.com)  Mon Feb  6 22:13:40 PST 2012


Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
EndSection

Section "Files"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Unknown"
    HorizSync       28.0 - 33.0
    VertRefresh     43.0 - 72.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BusID          "PCI:1:0:0"
    Option "SLI" "Auto"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

I don't dual boot, Linux is my only OS, I have spoken with several Windows users and they have stated that SLI works great in Windows, so seriously... perhaps Microsoft is paying Nvidia some extra $$ to keep Linux drivers hindered? It's just odd how bad it is, and linux has had SLI support for quite sometime now too... hmmm.

Any suggestions? Maybe my configuration is wrong, is it really a "Linux only" issue?

Last edited by Chaniyth (2012-02-17 03:03:16)

sakisds

Member

From: Athens, Greece

Registered: 2011-10-03

Posts: 105

Re: SLI enabled drops frames per second by half... any suggestions?

What are you using to measure your framerates? I have SLI disabled here since it makes gnome-shell run at 2FPS but I really haven't tried with anything else. I don't need both cards in Linux anyway.

brebs

Member

Registered: 2007-04-03

Posts: 3,742

Re: SLI enabled drops frames per second by half... any suggestions?

Probably better to report it on the Nvidia forum.