Help Needed - 2 graphics cards

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Level 1

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Help Needed - 2 graphics cards

I just bought a Radeon ATI 1900 G5 edition online for my PowerMac G5. I already have a GeForce 7800GT as the primary card but I thought the new card would double the performance. I also thought installation would be as simple as popping in the new card. Obviously I should've done my homework a little better.

Each card seems to need the extra power connection from the motherboard, but as far as I can tell, there is only one power cord.

What to do?

I run FCP5, Photoshop, and AfterEffects and I want as much graphics horse-power as the G5 will give me.

Is it possible to have both of these cards installed?

Advisable?

If so, how do I do it? Can one of them run without the external power cord? I assume I would use slots 1 and 3?

Please shed some light for me. I feel silly for having bought the card as it seems it may not help my situation. The customer service guy gave me the impression it was going to work fine.

Anyway, please give me some feedback soon if possible as I'm anxious to try out the new set-up.

Many thanks
S

G5 Quad-core 2.5Ghz 8GB RAM FCP5.1.4, Mac OS X (10.4.9)

Posted on Jun 24, 2007 8:15 PM

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Answer 1

Best reply

Malcolm Rayfield

Level 7

28,123 points

Jun 25, 2007 3:16 AM in response to pohnpeian

The only reason to use two graphics cards is to use more than two displays. You will not get more performance. The main difference between the cards is that the ATI Radeon X1900 GT Mac Edition can run two 30" displays at full resolution, while the Nvidia GeForce 7800GT can only use one. Also, the ATI card can provide S-video or composite video output. If you are not planning on ever getting two 30" displays, and will never need the video out, see which card works better with your applications. Otherwise, use the ATI card.

It might be possible to install both cards by making a custom power cable, but the second card could not run at full speed because only slot 1 (bottom slot) of the PCI-Express bus is 16x. The second card would have to go in slot 3 (8x). This slot has a lower power rating than slot 1, so the card may not work there, even with the auxiliary power cable. There is no reason to even try this if you don't have more than two displays.

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Answer 2

pohnpeian Author

Level 1

0 points

Jun 25, 2007 3:51 PM in response to Malcolm Rayfield

Thanks very much.

That helps me in knowing which card to use for the time-being.

So you're saying that two graphics cards would in no way boost performance in graphics apps like PS, AE, or FCP? That the only reason people use multiple cards is to have many monitors?

I thought the extra VRAM would help with my rendering and real-time effects, no?

Ever heard of anyone somehow using two cards? Do they make a splitter for the power connection? Or is it risky to have two cards running for power reasons? Or could the NVIDIA run without the power connection from slot 3?

I have no other PCI cards in there so I would run two if there was any benefit to be had. But I am only using two 23" monitors so maybe there isn't.

Thanks so much for replying though,
S

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Answer 3

The hatter

Level 9

60,990 points

Jun 25, 2007 4:13 PM in response to pohnpeian

Only on PCs where you can use something like Cross-Fire and then you need two full performance video slots. New video cards provide two GPUs.

AGP Radeons are in short or non-existent supply.

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Answer 4

Jun 25, 2007 7:07 PM in response to pohnpeian

So you're saying that two graphics cards would in no
way boost performance in graphics apps like PS, AE,
or FCP?

Some PCs use multiple graphics cards with SLI to increase performance, but Macs do not support this.

That the only reason people use multiple
cards is to have many monitors?

Correct (at least for a Mac).

I thought the extra VRAM would help with my rendering
and real-time effects, no?

The extra VRAM is on a different card, and without SLI to connect the cards, there is no way it can be used.

Ever heard of anyone somehow using two cards?

Not two high power cards,

Do they make a splitter for the power connection?

No. You would have to make your own. It wouldn't be too hard to splice two power cables.

Or is it risky to have two cards running for power reasons?

The total power consumption would probably be OK, but only slot 1 is rated for high power cards, and the auxiliary power was only planned for one card

Or could the NVIDIA run without the power connection from slot 3?

No. It can't even do that in slot 1, which provides a lot more power than slot 3.

I have no other PCI cards in there so I would run two
if there was any benefit to be had.

With no other cards, there is probably enough power, but it is spread over the low power slots 2, 3, and 4.

But I am only using two 23" monitors so maybe there isn't.

The extra card would just be using power and producing heat.

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