The 5770 almost certainly needs a 6-pin power cable but there are some twin 4-pin MOLEX to 6-pin GPU cables that were used. Normally since the Mac Pro already has one or even two 6-pin cables you should just be able to use those.
The 5770 almost certainly needs a 6-pin power cable but there are some twin 4-pin MOLEX to 6-pin GPU cables that were used. Normally since the Mac Pro already has one or even two 6-pin cables you should just be able to use those.
If you buy a genuine Apple 5770 card it should come with the correct power cable.
If you buy a PC 5770 as you state, you will need to purchase this power cable. Also unless you flash it, you will be missing several features, most notably boot screens.