5870 and 5770 power

[The-Pro]

I have no idea.

I think the 6-pin video power connector is rated for 75 watts. If you can find out how much the SATA power connector is rated for, that would give you an answer.

Forget that. SATA ports don't provide anywhere near enough power. 12W or something like that, not sure.

But do you know if it would work powering a GTX 580 from the disk power?

GTX 580 uses like 300W under load doesn't it? You will have to have an extra PSU to power it.
Redneck1089, I think you misunderstood what was said before with the PSU detecting power from a SATA connector. The electricity coming from the SATA connector is not used for powering anything. It is connected to the extra PSU in the optical drive bay so that when the MacPro is turned on the extra PSU is turned on aswell which powers the extra GPU. It detects power from the SATA connector and turns on, the extra PSU will still have to be connected to a power socket.

 

[slughead]

But do you know if it would work powering a GTX 580 from the disk power?

The 580 is a hog, you need a second PSU