The SLI widescreen thing

[G_S]

Hi yall,

I have been following the woes of people on a few different forums who were trying to get their SLI rigs to work on widescreen monitors. Here's a quick rundown of problems I share with most people...

My sys:
Dell 2405FPW 24" widescreen
Athlon fx-55
gigabyte 6800 ultras x 2 in SLI
asus a8n sli deluxe
2gigs corsair

* in 1920x1200, window's desktop displays thin gray bar at top of screen. If I run with A)no sli B)a resolution lower than 1920x1200 or C)run the app full screen, then the bar disppears

* When running games (hl2, doom3, painkiller) at 1920x1200 SLI (single card 1920x1200 is fine) screen gets extremely jittery

There's one thing that I haven't seen anybody mention though. When I run Far Cry at 1920x1200 in SLI mode it runs fine. So wtf I said. What's different about this game? Come to find out that Far Cry is one of the only games that runs SLI in SFR (Split Frame Rendering) mode as opposed to AFR (Alternate Frame Rendering) mode.

So is there a way to force the drivers or change the game's profile to use SFR instead of AFR. I'd like to give it a shot and see if it works for hl2 etc.

 

[Dr. X]

I believe you can edit the game's profile under the driver cp to use either mode. The profile that comes with the driver is set up for a certain mode, but I'm pretty sure it can be changed. Mind you, I have no experience doing this, but I think it's possible.

 

[G_S]

Nothing in the control applet, but looking around online, I found this....I'll have to give it a try...

You have to edit C:\WINDOWS\system32\nvapps.xml

The "multichip_rendering_mode" parameter, sets the predefined Single ot Multi GPU mode for the given application in Nvidia's application profiles. It can have 3 main values, and they are:
"1" for Multi GPU AFR mode
"2" for Multi GPU SFR mode
"4" for Single GPU mode

 

[G_S]

Hmmm bummer. I can't get it to work. I edited the .xml file restarted my computer like it said to do but it still runs Halflife 2 in AFR mode

 

[ohnnyj]

What driver version are you using? The latest 71.84 officials allow you to change the mode by adding/changing profiles within the driver control panel.

On the nZone they have a walkthrough on how to change modes. You must first enable Coolbits in the registry.

 

[G_S]

What driver version are you using? The latest 71.84 officials allow you to change the mode by adding/changing profiles within the driver control panel.

On the nZone they have a walkthrough on how to change modes. You must first enable Coolbits in the registry.

It works! I set HL2, UT2004, etc to run SFR and no more jittering in 1920x1200! I'll have to experiment and see what the performance differences are between AFR and SFR. See if I'm losing out at all by using SFR instead but anyway...

Hey thanks for pointing me in the right direction!

Now the only thing I have to do is figure out how to get rid of that damn gray line at the top of my desktop sitting there taunting me. I'm thinking I'm just gonna have to wait for the next driver to fix that one

 

[GlimmerMan]

I have the 2005wfp and using 71.84.
For Farcar with DVI in 1680x1050, I see a horizontal band of jittering along the boundary were the split frame occurs. The jittering is not as bad as 6x.xx driver, but is noticible when I looked hard enough. And on the right side of the screen, there is a one inch vertical band where things look double-vision.
So I don't think forcing SFR will help in my case.