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.
How to install a Graphics Card into a Mac Pro March 7, 2015 13:24
Incredibly useful is this handy guide to show you how install a graphics card in a mac pro by apple_cards
First off you'll need to make sure the computer is turned off and also that the power cable is removed from the rear of the Mac. Then remove the side cover by pulling the lever at the back.
Once the side cover is off you'll want to discharge any static electricity you may be carrying by simply touching the PCI blanking plates on the rear of the Mac. Also it's advisable not to wander around too much during the installation in case you start picking up any other static from carpets etc..
Next locate the two screws attached to the plate that holds the PCI cards in place. These are thumb screws and should loosen by hand but there is also a philips screw head to get a screwdriver in there should they not come loose by hand.
You'll want to make sure that any handling of the cards is done by the cards edges. Try not to touch any of the connectors or components on the card itself. If there is already a card in place you'll need to remove it. On Mac Pro models 2006, 2007 & 2008 there is a small catch where the cards edge connector plugs in that will need to lifted gently to allow the card to slide out.
Some cards feature either one or two PCIe booster cables that supply additional wattage to the card. There may be a cable already present that you can use but if not you'll want to install the cables if your new card requires them.
The connection of these cables goes from the logic board to the card itself with the logic board connector being located just under the second hard drive bay on the 2006, 2007 & 2008 models or to the lower edge of the visible logic board just in front of the PCIe fan on the 2009 onwards models.
These can be a bit fiddly to install but be patient and you'll get there!
Now it's time to install the new card!
Slide the card into place on the lower PCIe slot so that the card sits flush with the base of the PCI bay. This will by default be the x16 lane on all models of Mac Pro. You can of course install the card in another slot if need be (if multiple cards are used).
I find it easier to have attached the PCIe booster cables into the card at this point before sliding it in, but plugging them in after is not a problem.
Now replace the bracket with the two thumb screws and tighten to ensure the card won't move when plugging cables into the rear of the card. Tighten these by hand as they are not likely to come loose and it helps if you need to change the card out in the future.
Now replace the side cover and push the latch on the rear in to lock the side cover in place.