Ooh! Goody. Go ahead and leave the ATI in if you aren't having any trouble and haven't removed it already.

EDIT: Go ahead and update your bios also, and them post the out put of /proc/mtrr.

EDIT 2: Sorry, misread. Ignore the BIOS coment.

I have no idea what happened between now and the last boot, but suddenly with the ATI card your dmesg magically became only as bad as the Nvidia. We can work with this and do everything in one big step, rather than solving one problem with the Nvidia, the solving another with the ATI. Either way, all my previous instructions stand.

Now, when you say it boots fine, in what sense do you mean? Can you just boot your system into RL 5, or can you actually use it somewhat without it going all crazy on you?

BIOS is already up-to-date ... last update was 2008, unless you know something I don't?

Here's system info via ATI native session with PAT disabled:
http://deesto.pastebin.com/v3Q2aCps

OK ... no idea either. I haven't un/reinstalled packages or played with settings in between changing cards.

I am basically back to "normal" booting with a somewhat normal Gnome session, though I'm not stressing the system or opening many windows, just gathering info. When I move a window, the move action responds fairly well, but there's some visible glitch-ing going on in the moving window during the move. I'd like to get back to KDE eventually, but I don't want to jinx anything at this point.

Sorry, I misread your post there.

Weird. Probably a software conflict. For now stick with Gnome, we'll install KDE again after we're finished.

OK ... so editing mtrr went fine, until the last line, which responds back with an "invalid argument" error ... I assume that's because "6" was already disabled in the second line ... if that's the case, and this should be a 2 instead, let me know ... otherwise, the system hasn't crashed yet, just really slow since "disable=0".

Are we getting way off topic here? Should we move this to another topic, even though the ATI bit isn;'t really solved yet?

Good to hear about the mtrrs. You have no idea how FREAKING GLAD I am to hear we got that one on the first shot. It would have been very painful otherwise.

I'd prefer not to move it at this point, to much useful information in this thread. I'd hate to have to jump between two different threads for reference.

More info in a minute.

Okay, I missed that you had disabled PAT with the ATI card on that last boot. That's what solved all the weird issues. Keep PAT disabled.

Just a sec now, let me try and figure out the correct MTRR settings. Hold off on the kernel for now, this might not be as bad as I thought previously....

Okay, boot into your system and we are going to disable some mtrrs again. Use the same order that worked for you the last time, but now only disable registers #2-6. If I read everything correctly that should be close enough to correct that you will notice a huge increase in performance.

Tell me if it works. I have my fingers crossed over here.

Sorry, I forgot to mention, that should be a 2 at the end. But I don't think that should make a big difference. I'll explain why when we figure this out.

OK, after rebooting and disabling 2-6 in MTRR (still 'nopat' in grub):
http://deesto.pastebin.com/MPKPp8R2

I don't notice much of a difference, but I don't know what I'm looking for ....

Are you getting any more of the weird, glitchy graphics you were getting before?

Yeah, a little. But not terrible. Maybe you can give me a test to run? For instance: a generic 'glxgears' is reporting ~1560 FPS.

Unless you're gaming, you won't notice much of a difference beside no more glitchy graphics if it is set correctly (at least not immediately). However, the overall performance gain should be substantial.

If your graphics aren't flaking anymore, like you said, let's go ahead and get back to the original issue. I'm assuming at this point you can use your desktop pretty much without errors (no crashes or slowdowns if you try to open multiple windows, etc., like you were having before). If this is true, move on to the next paragraph: we have corrected your /proc/mtrr to the best of our abilities. If you are still having problems, tell me: we'll have to go back and mess with the MTRRs some more.

Between this and disabling PAT, we seem to have solved the major underlying issues here.

Now, you have the open source ATI drivers installed? Can you enable compositing now? I think Adam said you have to install the mesa-experimental drivers or something like that in order to take advantage of this. If everything else is working all right, go ahead and do this and see if you can now get compositing support.

I have to run out now. I'll be back in less than 2 hours.

Your assumptions seem correct: no crashes or errors so far on desktop (except for occasional GConf/ORBit errors). mesa drivers were still installed since many posts ago. In Gnome, I can enable compositing (via Compiz desktop effects settings), though I noticed that the "wobble windows", while I can select it and it works, seems to disable itself every time I run the Gnome Desktop Effects config tool. Strange. And Xorf.conf is minimal, but calls for radeon driver.