Can I flash a PC Radeon 5870 for use in a Mac Pro? I have a Mid-2010 Mac Pro, Single CPU, MC560LL/A. It's equipped with the Apple-provided Radeon 5770.

However, I have a Radeon 5870 from my old PC lying around. I know I can't directly use it, but I wonder if there's a way to flash it to work with the Mac?
Yes you can. Netkas has a ROM at that link that works for 5870s.

You might also get by without flashing by going the Hackintosh route and adding some kexts