Best Mac Pro Graphics

Notes and Comments:

I have a 2nd gen. Mac Pro with DDR2 @800 MHz with a ATI Radeon HD 2600.

1. The ONLY graphics upgrade I can find that is a SURE BET is the ATI Radeon HD 4870 512 MB. Can someone suggest a DIFFERENT CARD that is a SURE BET? ** (All the other cards I've looked at, e.g. (BFG) nVidia GTX 2600, are problematic: either I'm missing a spec I cannot find or there's a question about system requirements that I can't answer).
2. Failure of "About This Mac" and "More Info." Unbelievably, under Hardware, there is no category for PCI. That's stupid. You have to go to Display and infer information about PCI specs from the graphics card, and this information is incomplete. I need to find out if I have PCIe 2.0 or 1.0. I need to know if I have one or two PCIe X16 slots? (Yeah, I could open the box). Can anyone answer either of these questions?
3. I've never been a gamer (yeah, Frozen Bubble on Linux; Mahjong SL is my first software that requires improved graphics, so I'm learning about graphics card specs for the first time. This BLOWS my mind: One of the most important pieces of information--OS compatibility--is often hiding. I spent time at the bfg.tech website. It has a great wiki and diagrams on the PCI bus, but can I search for Mac OS compatible cards? No way! I'm wasting my time looking at cards, never sure whether they support Mac or PC. Maybe I could infer this from the specs. For example, is SLI Mac or PC or both? And how about Open GL? If someone could specify for me "Mac specs only" and PCspecs only" then when I go to display card sites I could infer OS compatibility. Why can't I just search for Mac cards??
4. I know there's a SL bias favoring ATI over nVidia. (Or is it the other way around?) Why is this? How much does it matter?

The problem you have is that the firmware in your Mac Pro limits your available options for upgrading your video card. If you had a 2008 Mac Pro or later, you could have upgraded to a Nvidia GTX 285. The best card you can get for your Mac Pro is the ATI 4890.

Insofar as I'm aware, SLI is not supported under OSX. You can, however, buy a second video card such as the Nvidia 7300GT if you need two monitors.

Unless you're willing to flash cards, you need to ensure you're buying the mac edition of the card you're interested in. Macrumors.com is a good place to ask for more details about what cards are available for your Mac.

Re: If you had a 2008 Mac Pro or later, I DO have a 2008 Mac Pro, 2nd generation with 800MHz RAM. Was that a typo? If not, what's the best card compatible with 2008?

In this instance, what you have then is a third generation Mac Pro. The second generation is the 2007 iteration - which is what I thought you had based on your initial post.

At any rate, you should be able to use the Nvidia GTX 285 Mac Edition. This is currently the best Nvidia card available for your 2008 Mac Pro: .

Unfortunately, this will set you back by 450 USD unless you're willing to buy a PC variant and flash it.