Two different graphics cards in Mac Pro

Question

Two different graphics cards in Mac Pro

Hey,

Finally made the switch from PC to Mac woohoo!
However, because I needed my computer quicker, for work deadlines, than ordering over the internet could provide me (three weeks) I had to get a ready-configured setup from a store and get a couple of changes made. One thing was that the computer had a nvidia 7300 card, and I wanted the ATI one. They told me that I would still own the 7300 since it came with the computer, and that they would take it out, put it in a box and I could sell it on ebay or something. But... when I got the computer and checked all the hardware and everything, I found that they've put the ATI card in slot 1 and left the 7300 in slot 2.
So what I'm wondering is, does this actually mean anything or make any difference practically? I know that, for example, hardcore gamers like to have two of the same graphics cards in their machines, but I wondering whether having two different ones means they can work together and make my machine a little more powerful, or whether that card's just sitting there obsolete?!?!

Thank you in advance for your help!

Steve

Mac Pro 2.66, Mac OS X (10.4.9)

Posted on May 18, 2007 6:44 PM

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Answer 1

May 18, 2007 7:01 PM in response to kinkersnick127

Quite a few people have had problems with two cards. Your second card really won't be doing much unless you need to drive three monitors. A program like Aperture can use the power of the 1900 but it won't be trying to access both gpu and having two separate cards may turn out to be a problem. I'd just pull the 7300.

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Answer 2

May 20, 2007 12:07 PM in response to kinkersnick127

One monitor, or two?

If one, pull it - it's not doing a bit of good. However, one advantage of two graphics cards with two screens is calibration. With two screens running from a single card, it's not possible to accurately calibrate both (making changes for one affects the other). Two cards means accurate calibration for both screens.

If you're running two screens and concerned with monitor calibration, you might as well try to use them. Apple recommends that you DON'T run different graphics cards, but some have seemed to get away with it without problems. But, as mentioned ... some haven't.

-phil

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Answer 3

May 20, 2007 3:07 PM in response to Phil Shockley

You are kidding, right? You really can't calibrate 2 monitors on the same card?

Is Apple nuts? How can someone effectively use two 30" displays with the x1900 if you can't calibrate both monitors?!

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Answer 4

May 20, 2007 3:58 PM in response to neenach2002

Nope, not kidding. It's not really Apple's fault - it's just the nature of the beast. When you calibrate one screen, you're altering the card's LUT (look up table), which enables calibration. When you alter it for one screen, it will also affect the other.

That said, it may be the X1900 XT has separate LUTs for each video port (which would take care of the issue), but I don't know if that's the case. Even if not, it's not that big of a deal as most people only need one color critical screen.

(I did some digging on Apple's and ATI's site to see if I could find any LUT info but didn't see anything.)

-phil

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Answer 5

May 22, 2007 4:58 AM in response to Phil Shockley

Yep, only one monitor so I've pulled the card out and eaten it with a lick of butter. Not bad.

Maybe one day I'll have 3 30" monitors and it will be useful...

Thanks for the advice.

Steve

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Answer 6

icurate

Level 1

15 points

May 24, 2007 4:41 PM in response to Phil Shockley

As part of specing out my new Mac Pro I looked into this. The X1900 definitely has seperate color control for each output.
http://ati.amd.com/products/radeonx1900/specs.html

Dual 2.5 G5 Mac OS X (10.4.9)

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Answer 7

Brian Peat

Level 6

18,216 points

May 24, 2007 5:19 PM in response to icurate

Hmmm. I can change profiles on my Dell 20" connected to port 2 on my X1900 and it does not in ANY way change the colors on my Apple 20" connected to port 1. I can pick any profile and nothing changes visually on the other screen.

If what you're saying is true, wouldn't I see the Apple screen change color when I change the Dell?

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Answer 8

May 24, 2007 5:33 PM in response to Brian Peat

Calibration is controlled by LUT, while profiles are controlled by software (I believe). So no. But apparently, the x1900 has 2 LUTs on it (one for each port).

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