From what I see (and I just want to make sure I'm not missing anything obvious), the only way to get the full potential of two video cards on a Mac Pro tower is to run Windows on it? I'm coming from the Windows world myself, so I really have no aversion to running Windows, but I just bought this Mac Pro tower (2x Quad Core 2.26, 14gb ram, 4870 512mb Radeon, full specs here) and went straight out and bought 2x 5770s on the cheap to chuck in here because I heard that 1x 5770 underperforms a single 4870, but two will do just fine. I run twin nvidia 460s in SLI on my Windows Rig, and just didn't even think twice that Mac Pros wouldn't be able to support this setup. I'm a little shocked, but want to ask the obvious, otherwise unasked question that comes to mind: Is there ANY benefit to running these two cards simultaneously if I won't be booting into Windows on this rig? Other than powering 6 screens or something silly? I have a single monitor on this Mac, but can Macs offload Physics processing or anything like how the nVidia setups can in SLI? Have one card dedicated to chugging out frames and the other solely thinking about ragdoll/particles, etc? Thanks all. Been trolling around here a bit since venturing into Mac land forreals, looks like a helpful place.