As most of you know I bought a second 8800 GTS 512 to put into my system in an SLI configuration. My system configuration:
Coolermaster Cavalier (Mid-Tower ATX)
EVGA NVidia NForce 780i (BIOS P08/NForce Driver 15.23)
Intel E6750 Conroe 2.66Ghz (1333 FSB/4 Mb L2 cache)
Kingston HyperX DDR2 800 4x1Gb (4-4-4-12 @ 2.0V)
EVGA 8800 GTS G92 512 (Driver 178.13)
Creative Sound Blaster X-Fi XtremeGamer Fatal1ty Pro (Driver 5.12.6.1186)
PC Power & Cooling S75QB 750W PSU (+12V @ 60A Single Rail)
Seagate Barracuda 250 Gb SATA HD (Boot Drive)
Seagate 200 Gb ATA HD (Storage Drive)
Seagate 160 Gb ATA HD (Back-up Drive)
Asus SATA 20x DVD+R DVD Burner
Asus SATA DVD-ROM
Microsoft Windows XP Pro With SP3
LG 22" 2ms Widescreen LCD
Klipsch Promedia 78 watts 2.1 Speaker
I got the second card added and configured for SLI. I entered Aces High II with vsync and triple buffering enabled and was running at almost 285 FPS. This was well above the 60 Hz refresh rate of my monitor and, as I jumped into a plane I was experiencing graphic tearing as well as game stuttering so I exited the game and went to the Aces High video settings where I turned off unlimited frame rate and locked it at 60. I re-entered the game with my frame rates running between 63-65 and was still experiencing tearing and stuttering. No combination of control panal settings would eliminate the problem.
After much research and reading I uninstalled then re-installd my video drivers, turned off triple buffering and vsync and re-set the game video settings to allow unlimited frame rates. I entered the game running 16x anistropic filtering and 16x antiaiasing. This smoothed the stuttering considerably but I was still experiencing some tearing. Frame rates were between 220 and 285 in the air and between 65 and 105 on the ground, likely CPU limited.
I then tried to induce vsync using RivaTuner's D3DOverider utility. It made no difference as my frame rates were still running over 200.
Next I tested each video card independently with vsync and triple buffering on at AFx16 and AAx16. Each card played the game smoothly with no tearing and no stuttering at 59-60 FPS regardless of what type of situation I was in. The only noticable drawback was that response time to snap view changes were slowed slightly.
Since I had first tested the top card alone, then removed it to test the bottom card in the top slot I tried to SLI again with the cards reversed from their previous positions. The results were the same as before.
While the tearing and stuttering produced in-game by the SLI configurations was minimal, it was still annoying. Massive frame rates sound good on the surface but I found that a smooth gaming experience is far more preferable and since I've discovered that my single card can provide that at 16x AF and 16x AA at my monitor's refresh rate I have removed the second card and will RMA it Monday (unless someone wants a perfectly good 8800 GTS 512 for what I paid for it).
I still like the concept of SLI but with todays LCD displays until Nvidia (or someone else) can find a way to force vsync in SLI mode I think it's best left alone.
