Radeon 4870 in 2006 Mac Pro?

This thing came with a X1900 and it's beginning to show age. Will the new card with the new Mac Pros work in this bitch? Better yet, could I Crossfire these two?

I believe PCI Express 2.0 is required for the new cards. I doubt crossfire is supported in OSX, but maybe it would work in Windows? I'm not sure.

Not sure it would work in an '06 Mac Pro. Besides not being PCI-E 2.0, the '06s also have 32-bit EFI (which caused a flap when '06 owners wanted to install the then-new 8800GT in their rigs). I believe you can use a 32-bit compliant card in a 64-bit EFI machine, but not the other way 'round.

That being said, I wonder what the 4870 costs stand-alone, as I think I'd like to slide one into my '08 Mac Pro. I also wonder if the 4870 X2 would work with a Mac-compatible BIOS flashed onto it...

Well lookie what I just found:

http://store.apple.com/us/product/MB999ZM/A

Looks like no love for '06 MP's, I'm guessing for the reasons posted. Sorry Zilla.