PCIe x4 Graphics Card's for Mac Pro's?

[Mythlin]

Hello,
I'm looking to buy a Late 2008 8 Core Used Mac Pro. I've found the Mac Pro I would like to buy. But, I was wondering if anyone knows if they make or where they sell any PCIe x4 Graphics Cards. I'm going to buy two 5770's when I purchase the machine but would like to have even more graphics performance (if possible) by having four graphics cards. I'm going to be running six 1920x1080 displays. So yes, two 5770's would run those Six Displays. But, that's not what I'm trying to go for.

If anyone has any info on PCIe x4 Graphics Cards for the Mac Pro, it would be greatly appreciated!

 

[Cindori]

you won't get more performance by adding more cards since OSX does not support crossfire or SLI.

 

[Mythlin]

I understand that, but. I need to run Six Displays. They are DVI Displays, so, that means. If I used two 5770's. I would need to buy "Active" Mini-DisplayPort to DVI adapters. And I would need to buy 4 of those which becomes expensive.. fast! Even if using a third-party one. But.. If I had more than 2 graphics cards. I could essentially run the less graphical intensive stuff on those graphics cards, and still have 6 displays. Which is what I would really like. I just don't know where to get that kind of card:/

 

[flatfoot]

As far as I know, you can put any 8x or 16x graphics card into a 4x slot as long as the slot is full length, which is true in case of the Mac Pro.
The card just won't perform as it would in a 16x slot.