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Old 04-05-07, 10:37 AM   #1
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Join Date: Apr 2007
Posts: 10
Default OpenGL performance issues on SLI'd GeForce 8800's

I am running into a performance problem with the NVIDIA GeForce 8800 GTS on a Opteron platform when in SLI mode. It seems as though OpenGL performance while SLI is enabled is extremely poor.

My system configuration is the following:

4U chassis with a 1000 watt high efficiency power supply
(2) Opteron 2220 (2.8 GHz) Socket 1207 processors
(8) 2 GB DDR2-667 memory modules
146 GB SAS local disk
(2) NVIDIA GeForce 8800 GTS (640MB) hardware configured in SLI mode

I have attempted SLI on both SLES10, as well as RHEL4 with a 2.6.20 kernel having module support included by the NVIDIA linux binary, however replicated the same issue on both platforms.

When I have in my xorg.conf file `Option "SLI" "0"` with this hardware configuration I get about 22,000 frames per second when running glxgears however when I enable SLI by using `Option "SLI" "1"` or `Option "SLI" "AFRofAA"` I run into a terrifying performance hit. Running glxgears I get about ** 2.4 to 2.6 frames per second. **

I attempted to contact PNY about this (the manufacturer of my card) and they told me that they "Don't support Linux".

I fear there is a complication in my hardware configuration with the 8800 GTS configured in SLI mode. I say this because I replace my (2) 8800 GTS's with (2) Quadro 4500's configured in SLI and I get no such performance hit.

Please, if anyone has insight on this, I would greatly appreciate it!

Debug information which may or may not be usefull...

/etc/X11/xorg.conf file:

/var/log/Xorg.0.log file:

Linux version 2.6.20 (root@ls1host) (gcc version 3.4.5 20051201 (Red Hat 3.4.5-2)) #1 SMP Wed Apr 4 21:07:57 MDT 2007

NVIDIA module:

BIOS version:
TYAN BIOS version 1.1
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