Will additional PCI gfx card slow down PowerMac G5 general graphics performance?

[philosophish]

Hello,

Preliminaries:

1) I am in the possession of a June 2004 PowerMac G5 DP 1.8.
2) It's the AGP+PCI variety (not PCI-X, not PCIe).
3) It's running Leopard 10.5.8
4) I've got an Ultra 6800 DDL installed.

Main Question:
What is the best way to add another (3rd) monitor?

Considerations:
I think it means adding in a PCI graphics cards, none of which support CoreImage (and QuartzExtreme neither, without PCI-Extreme).
NOTE: I am using a Kensington USB DualLink on my MBP for 3rd screen, but even though it works under SnowLeopard performance is, well, not so great (only a beta driver).

I've got my eyes on a (original Mac Ed) ATI RADEON 9200 128MB. (Is there a better/faster PCI card for the G5?)

Now, will the lack of QE and CI in the PCI card slow down/reduce OSX graphics capabilities for the screens connected to the Ultra 6800? Or can OSX run them independently i.e. apps requiring CI/QE will work on one monitor, but not on the other?

Side question:
In fact right now there is somebode selling a PCI FX5200 with 256MB and two VGA-outputs in the bay , claiming it can do BOTH CI+QE, IF run as the ONLY graphics card; is there any substance to this? What, why, how?
I personally am doubtful, since I thought that CI required AGP x2 or better, which PCI obviously isn't. Thanks.

NOTE: you'll find it on the .com site by search terms "NVIDIA GeForce FX5200 PCI Mac 256MB Xserve"; don't mean to advertise for the guy or anything, just curious.


Thanks a lot
phish

 

[goMac]

OS X can use CI/QE on one display but not the other. When rendering on the display on the other GPU, it'll fallback to software rendering.

 

[disconap]

Can't you disable them in software though? Then adding a card to, say, just keep mail and calendar open in (or whatever function you need) would make perfect sense...

 

[philosophish]

Hello, thanks for your answers.

@disconap: Yes, that would be my intention. I have one (central) working screen, one for auxiliary tools (palettes, tooboxes, whatever) and prefer to have a third screen to keep email and the like open; I wouldn't need CI/QE there, I just want to make sure that they won't be turned off on the capable two screens by the lacking card/display (as in greatest common divisor). I admin that it is a bit spoilt, since I could make do with window shuffling, but I prefer it like this.

@goMac: Do you mean that OSX generally does not support CI/QE on more than one display or that one display is unaffected by the other's capabilities or lack thereof?

regards
phish