I already have a lot of experience that stuff from nvidia does not just work either and no real hope of that getting better. If you only run two monitors it is fine. If you run 4 with two video cards then it is not so trouble free.
The eyefinity 6 card can do 6 monitors in hardware so no xinerama needed anymore as long as eyefinity works under linux. The whole thing is presented as a single display to xorg or at least theoretically. So even things like composite should work and amd has shown far more interest in open source then nvidia has.
They may not be better now but it sure looks like it will long term. Right now as long as it is better for running 4 displays for 2d work quicker then dual 8800GTS with xinerama that is what I really care about. 3D is not important to me.
I don't need 3D at all right now. Fast 2D is mostly want I want and composite would be very nice to have. My understanding though is that with eyefinity 3D does work at least well enough for anything that kwin would use for desktop effects.
I don't care about any gaming though or running actual 3D apps. When I run just two monitors and can enable desktop effects the system is FAR faster. You can move windows around without lagging, they show up faster, far lower cpu load when using them. Even scrolling webpages used up a lot less cpu time.
However running two monitors or two sets of two monitors is a major pain. 4 monitors is much more productive since I can see my code, output, logs, docs etc at the same time. Eyefinity should be the solution to this problem. I just don't know if it really works yet on linux. If it doesn't I will wait and just live with the nvidia problems for a while but would prefer not to.
With Xorg 1.7 xinerama is pretty much broken. At random times when moving the mouse between monitors it will get stuck between them and Xorg will be frozen and just use up more and more memory. I have not seen any good patches for that yet either. Xinerama has been screwed up many times over the last few years of X releases. I would like to get completely away from it and still use 4 monitors.
xrandr still does not support mutli-gpu objects which is needed to turn them all into a single screen. So even with nouveau you have to deal with xinerama to make a 4 screen setup or at least that is my understanding of it. So that might make some 2D stuff faster but I would still have xinerama bugs to deal with..
The quadro cards that can run 4 1920x1200 monitors in a 4x1 setup where very expensive last I checked. They also are FAR too loud and hot. The 5000 series ati card are quieter and far lower power usage.
Active dvi/hdmi connectors are $100 but active vga connectors are $10 and the quality output between hdmi and vga seems to be identical.
I really doubt that. Have you tried displaying high-contrast images or grid patterns? With VGA, there's often ghosting and moire patterns. Especially at high resolutions, the VGA interface wasn't really meant for those bandwidths.
At least that is my experience with a recent (~1.5 years old) 1920x1200 TFT monitor. 1024x768 works fine, but at 1920x1200 the image gets really ugly.
There's also something about apple adapters, from what I heard they depend on some specific capabilities of the GPU only found in apple products, i.e. they don't work anywhere else. Not sure though, I never tried.
You're right about eyefinity: no server-side Xinerama, acceleration across all monitors without trouble. If eyefinity is fully supported, that is - I haven't used more than 2 monitors so far.
There's only two solution to have >=3 monitors without Xinerama: get a card with enough outputs (eyefinity) or get a matrox triplehead2go (you could call it a dvi splitter).
It does seem strange but I have 4 Westinghouse L2410NM which are PVA screens. I get no moire patterns or any other distortion switching back and forth between hdmi input and vga input. I have even done stuff like just switching the monitor back and forth between the two inputs with the same desktop up on both inputs and could not see any difference at all in images, text etc.
I know those adapters say they are for apple stuff on that page but I did some searching around and people where using them with eyefinity cards also without problems apparently. There are some short stuby ones that are displayport to vga that people have some problems with but overall work. The mini displayport one though that I gave a link to is supposed to work much better since it hands over all the EDID information among other things.
thanks for the changelog info...got me pretty excited but well i started looking for an adapter i found, surprisingly, that the stuff i heard from a dude at Fry's regarding displayport was accurate:
1) To use Eyefinity you need to have at least 1 "native" displayport device, this can be a monitor with displayport, or native adapter.
2) The cheaper adapters, like the ones you posted, are actually "passive" adapters, and I guess cause ATI cards to use their standard VGA/DVI hardware rather than the 3rd displayport one.
3) The only "native" adapter out there i've seen so far is $100 http://www.amazon.com/Accell-UltraAV...ref=pd_sim_e_3
So for us frugal folks I think eyefinity only makes sense if we have a displayport monitor, or a REASONABLY priced active adapter comes along.
Seems to me AMD/ATI is using eyefinity to push displayport adoption, since their eyefinity 6 cards can push a signal over a non-active adapter for the first 4 devices without any issues (or so i've read, in this forum i think).
fortunately ATI supports xrandr and i can toggle between 2 secondary displays with a keyboard shortcut, which works for me since my 3rd output is just a TV i use to watch videos and whatnot.
Hmm from what I read online all VGA adapters are active. The dvi/hdmi adapters that look like that are passive though. However because the VGA signal is analog and not digital and the cards don't output analog all analog adapters have to change the signal.
At least on various sites I have looked at they have said that all the vga adapters are active ones.