The Mac Pro power specs are considered to be about 75W max to each PCIe slot, plus 75W max per each 6-pin PCIe power adapter for a maximum single internal PCIe card draw of 225W (75W + 75W +75W). Some folks bring down one of the four-pin Molex peripheral power plugs from the ODD bays into the PCI area since they are typically thought of as max 187W so they can drive an 8-pin PCIe max 150W, but then you're playing on the edges of balancing all the power across the main Mac Pro PSU (bigger CPU? lots of RAM? Bluray?), especially if you already have a lot of drives taking power. It's also not clear how much power the Mac Pro ODD Molex plugs can really provide reliably as they were intended for 15W-25W DVD drives!
That's why most people with a Mac Pro look for cards that can properly run with two 6-pin PCIe power connections or less. The MSI has one 6-pin and one 8-pin, but it ships with a 6-pin-to-8-pin connector in the box, which is what originally gave people hope that it'd be <=225W draw. It seems to work, which is what got me to try this card. Even then, the card is spec'd at 250W by many reviews so there is some risk that pushing the GPU to the edge (which doesn't seem to happen in even intense gaming, but perhaps possible with big video rendering tasks) might push it beyond the max the Mac Pro can provide. It's also unclear what version of the card a review uses that states the 250W, as there seems to have been at least two different ones so my second version may be a bit more power efficient and that's all the difference? All I know is that the MSI works for me, and seems to work for others, that's why I posted the exact model I have for guidance.
its bricked
