SOLVED: 310, two cards, four heads with rotation

After years of using four heads on two GTS 250 cards with drivers up to 295, I was suddenly unable to get this working with the 3xx series. Today, after having my hand forced by an upgrade to 650 Ti’s, I was able to get things working with driver 310 (though it may also work with 304). The key is that the “Rotate” option no longer works, so one must use the “MetaModes” option with “{ Rotation=left }” to achieve the same effect as “Rotate” “Left”.

Note that this is a 4-headed Xinerama setup with no RandR or TwinView, meaning no dynamic transforms, which still makes me sad. But, on the bright side, VDPAU and OpenGL still work.

Here are my configs for 295 and 310, as well as a photo of my setup so you know what it’s trying to drive.

http://www.krose.org/~krose/static/xorg.conf.nvidia-295
http://www.krose.org/~krose/static/xorg.conf.nvidia-310

Note that you should be able to drive all four of these off a single GTX 650 Ti without requiring to use Xinerama assuming you have a model with four connectors.

You can also optimize the current case by having 2 X screens, each spanning two display devices instead of 4 X screens. Each additional X screen in Xinerama increases overhead so using the least amount possible is recommended.

Pierre, I have only 3 digital connectors: 2 DVI, 1 HDMI, and 1 VGA. I suppose I could use the VGA for one of my screens. I’m fine with having two cards. I actually tried to find a card with four digital ports, but couldn’t.

How do I set this up with 2 X screens? Does the window manager get geometry such that it still understands that there are 4 logical displays so it doesn’t, for instance, try to maximize a window across 2 displays?

If you’re willing to use the analog output for one of your screens, it would free you of having Xinerama; you could use composite managers, dynamic RandR, and performance and memory usage would be a lot better across the board. Display geometry would be reported correctly in that case, but you’re right that in a “Xinerama-of-TwinView” case such like the one I described above your windows would maximize across two displays. It’s something we’re tracking as an enhancement. Just for reference, to configure a mode like that you would use two X screens, each with a MetaMode that tracks two display devices side-by-side.

I imagine your power consumption would go down too, with 1 card instead of 2.

I’ll worry about that next summer. Right now, in autumn in New England, my computer is a nearly 100% efficient space heater: any light that doesn’t escape the windows is turned into heat energy that simply replaces the natural gas I would otherwise be burning. :-)

So, just for laughs, I implemented the single card solution with all four inputs. It works fine with a good quality VGA cable. (My run is 15 feet, so I avoided analog because I suspected interference would be more of a problem.) It’s certainly an easier config, and as a bonus dynamic RandR works. So, I’ll probably keep it this way and use the other card for a gaming rig. Thanks for all your help, Pierre.

can you post your current working config ?

I got a request for my new xorg.conf. Here it is:

http://www.krose.org/~krose/static/xorg.conf.nvidia-310-onecard