I couldn't find any references to anyone doing this yet and wanted to ask if I'm missing anything. I have a 2008 mac pro and 3-monitor setup. I originally started with 2 x ATI 2600's, but have since replaced one of them with a 3870. So, my current setup is 1 x 3870 and 1 x 2600. This setup has worked fine. Now that the 4870 is available, I'm looking to upgrade. I'd like to use 1 x 4870 and 1 x 3870. Obviously the 4870 would be the primary card and the one that bears the brunt of the GPU load, but I'd prefer the 3870 as the secondary card to the 2600 because the 3870 gives smoother performance with Quicktime in full screen for high-quality H.264 and also manages Spaces / Expose more fluidly, among other things. Plus, seems like a waste not to use it. The problem is the power - 3 PCI Express auxiliary power connections are required to run both cards. But I think I have a way to solve this. I can install a 4-pin molex splitter in the optical bay, and then use the included 4-pin molex to PCI Express power connection included with the 3870 along with a PCI Express power extension to feed power to the 3870, and then give the 4870 both of the motherboard power connectors. According to my research, I don't see much potential here for a power draw problem. The 3870 would be basically 2D only, and the max draw according to the table I found for 2D was somewhere in the 40 watt range, well within what the PCI Express slot itself will provide. Even in the freak condition that more power is required, the max draw was still under 100 watts, putting the draw on the auxiliary at 25 watts, which is comparable to one optical drive burning a DVD. Since it's highly unlikely that BOTH optical drives would be burning DVDs at the same time as maxing the video card out, I can't see how this could cause any stress on the power supply in terms of the power reserved for the optical bay (now split to the 3870) and the regular PCI Express power draw for both cards. Even if the power load was split between the bus and the auxiliary, that's still less than 50 watts on each, and theoretically the optical bay power can provide 50+ watts if it's within spec to burn 2 DVDs at once. But... am I missing anything? Or, has anyone else tried this? Thanks in advance!