Performance with 2 Graphics Cards?

[editonmac]

Hey everyone,

I just bought a NVidia GeForce GTX 650 graphics card from PNY. Put it in the machine (2009 MP running 10.8.2) and it works great! Great card.
So currently I have the GTX 650 in slot 1 and the stock GeForce GT 120 in slot 2. My question is, does having both cards in the machine decrease performance in any way?
If not, does it matter how my displays are hooked up? Currently I only run 2 displays (one 1920x1200 ASUS on the 650, and a 1080P Dell on the 120). Would having both of them plugged into the 650 change performance?
I mainly use this machine for FCP 7, FCP X, and Compressor 4. Any advice would be appreciated!

 

[minifridge1138]

Hey everyone,

I just bought a NVidia GeForce GTX 650 graphics card from PNY. Put it in the machine (2009 MP running 10.8.2) and it works great! Great card.
So currently I have the GTX 650 in slot 1 and the stock GeForce GT 120 in slot 2. My question is, does having both cards in the machine decrease performance in any way?
If not, does it matter how my displays are hooked up? Currently I only run 2 displays (one 1920x1200 ASUS on the 650, and a 1080P Dell on the 120). Would having both of them plugged into the 650 change performance?
I mainly use this machine for FCP 7, FCP X, and Compressor 4. Any advice would be appreciated!

I believe you'll get better performance by using 1 monitor per card. The VRAM is fixed for the card (2GB or whatever). So if you're using 1 card to drive 2 monitors, then each monitor has 1GB of ram (assuming all things are equal; which they never are).

Now is this a performance difference that you'll notice? Probably not.

I'd keep the GT120 in it simply because that should give you an EFI boot screen (if I'm not mistaken).