I know there's going to be a lot of theory thrown around here, but here's my issue. I've got a user with 5 displays hooked up to his box. 4 are on a quad head Nvidia. The 5th is some other PCI card I picked up at CompUSA. The 5th monitor has been in use for months now. There's been some added weight to the X-Server though, and it's noticeable.

Almost all applications are run remotely from a server and exported DISPLAY'ed on the client. The X process spikes up to 50% sometimes, which is causing me to be yelled at. The machine is a dual processor 3Ghz w/ a gig of memory running XFree86 v 4.3.0-r7 and KDE 3.3.0. All KDE GUI effects are turned off, and (I think) it's running in 16-bit color depth. The displays are at either 1920x1600 or 1600x1200 depending on the monitor.

I've cut all that can be cut. If the problem persists, I think my options are:
-Try Xorg
-Try Gnome

I just can't see any of the others offering that drastic of a performance.

Considering it'll take me all day to compile these (it's gentoo box) I'd be very glad to hear some other tweaks that might help. One thing would be if the 2nd graphics card which is only supporting one monitor is a cheesy card, could it hold back the other more powered card?

Thanks.

Well I'm a total noob, but on my Mandriva Linux 2005LE box my ATI video card there are about 4 different drivers all of which support it. The only difference I have detected between them is like you said the X server has sudden usage spikes. The other thing is the performance of the display, but this was a minimal difference.

My box is a AMD Athlon XP 3000+ w/ 1GB RAM so we are similar in that aspect. Other than that you are not using the best drivers for your video card is simply that there is a performance decrease for having more than one monitor. I believe that in windows only the primary display can have 3d acceleration but that could be limited to windows. does any one monitor seem to be faster than all of the others? Not to mention 1600X1200 is a huge resolution (by my standards I use 1024X786. My monitor goes higher but the refresh rate is crap and look nasty.) and on all 5 monitors at that. You may want to try cutting down the resolution all the monitors and see if that solves anything.

On my laptop the laptop screen max's out at 1024X768 and the external monitor i had set at 1280X1024. When i run windows XP on that laptop with that setup i notice a big performance decrease on the monitors until i make both monitor the same resolution and color depth. So far I have been unsuccessful in getting multi-monitor support working in linux so take my info with a grain of salt, I have no idea how much of what i said is true in linux. But hopefully something here helps.

There are 5 monitors b/c the user actually needs that much space. If I cut the resolution down to even 1280x1024 he'd be losing X percent of his screen space, so that's not a viable solution. To boot, there are 3 16:9 montiors and two 4:3, so even if there were two identical cards, the resolutions would be different. I assume that this wouldn't be too much of a hit on the Xserver. The 2nd card not being up to snuff sounds like a more viable problem point to me.

Driver update is the next logical step. I need to synch the whole system probably which I can't really do at the moment, but can later. Fingers crossed.

don't think xorg will help
xorg is just xfree86 basically still if not for ever
i notice they give the credit like out of the xfree liscense
it is unclear if or when they will or have just gone back to copying xfree which is all they have done for many many years