How much power can the Mac Pro provide for Graphics Cards? March 7, 2015 13:27
A question that appears a lot is how much power can the Mac Pro supply to graphics cards through the internal PCIe power cables and PCI slots. Here at apple_cards we shed some light on the power consumption of the most popular cards and some alternative solutions for the extra power hungry graphics cards out there!
The Mac Pro is a very well powered machine. The power supplies used in all models from 2006-2012 have a total output of 980 Watts which is then distributed throughout the machine to power various parts. The parts we are interested in are the wattage amounts that can be safely drawn through the PCI slots and the two AUX PCIe booster cables.
The technical specs show that each PCI socket can provide 75 Watts of power and each PCIe cable can supply 75 Watts each giving a total of 225 Watts that is allowed for a graphics card. Most graphics cards are well within this specification although there are some unofficial cards that require more than that at full load. For these cards we recommend an separate power supply to feed just the card itself. There are a few people how have modified their cases and installed some very neat solutions if you look here: Installing second power supply inside Mac Pro
Taking these DIY approaches aside you'll find that the vast majority of official Apple cards are well within the operating specifications of the mac pro such as the nVidia GTX680 with a power draw of 195 Watts (TDP), the AMD Radeon 7950 with a power draw of 200 Watts (TDP) and the ATI Radeon 5870 with a power draw of 228 Watts (TDP) which is pretty interesting considering the 225 Watt limit. There is scope for these cards to draw more power as they most likely under load will and despite rumours we have not seen anything bad happen other then the machine switching itself off if the power draw is too high.
So in summary the official 225 Watts has some room for movement but to be on the safe side you can always run the 'extra' power hungry cards from a separate PSU.