Updated Dec 20, 2014 (original – April 30, 2011)
This procedure for installing a PC R6870 Video Card into a Mac Pro works for Mac OS Yosemite and Marvericks as well as Mac OS X Lion with one change, you don’t have to load the drivers. From the release of Mac OS X Lion, the Mac OS software includes the necessary ATI Radeon HD 6870 drivers required for a Mac Pro. Unlike supported cards, the screen still starts out black while the OS is booting.
Recently I decided it was time to swap out my GeForce 8800 GT in my Mac Pro 3,1 for a new video card. I did a bunch of research and decided that for around $200 the ATI Radeon HD 6870 1 GB 256-bit GDDR5 PCI Express Twin Frozr II was the best price for performance card. This card is built on the ATI Radeon HD 6870 platform. The performance was far superior to my GeForce card, it is most likely the quietest card due to the huge heat sinks and two (instead of 1 like most video cards) fans, and has 2 DVI, 2 mini DisplayPort, and a HDMI port. Not that I need all those now, but suspect I will in the near future. Customer reviews confirmed it was quiet and ran cool. More reviews confirmed it ran on the Mac Pro 3,1 (Mac Pro early 2008 running 10.6.7). Now that I finally having it working and can attest that it is a very quiet card, as quiet as the GeForce 8800 GT that it replaced. Below I explain what it takes to get the card working.
Installed ATI Radeon HD 6870
After the card arrived I realized the sites I had reviewed were from people booting windows natively on their Mac Pro’s. Who knew there were so many people running windows on the Mac Pro. I spent the next several hours trying to find out how to get this card working. I read articles on how to flash it, complicated articles on downloading a variety of programs to change parts of Mac OS to get the card working. Finally, after extensive searching I found the drivers. This posting is a how-to guide and hopefully easier to find than the posting that I finally downloaded the drivers from.
Although I have only tried this with the MSI 6870, I suspect it will work for any other brand of the 6870. Please comment below if you get use these drivers on another R6870.
Before doing anything, download and install the drivers. This can be done while you wait for the card and power cable to ship to you.
The 8800 has a power cable that runs from the mother board to the video card. You will notice that there are two 6 pin connectors on the mother board right next to each other (see top left corner of picture below). The new cable will plug into the empty connector to provide two power cables to the new card.
Disconnect the power cable, unscrew the bar that holds the PCIe cards in place, and pull out the 8800 video card. Note that on the PCIe connector on the mother board there is a plastic catch that you will need to pull up to remove the card. If you don’t you will break this off. Not the end of the word, but not ideal.
There is a blue plastic cover over the PCIe connector that has to be remove before installation. Slide the card into the same slot you took the 8800 out of. Connect the two power cords and replace the bar that holds the PCIe cards in place. Close up the Mac and turn on.
When booting you don’t see the normal boot screen. The screen stays black until the Mac is booted then you see the login screen.
You are done!
I knew I made the right decision when I cranked up the WOW video setting to Ultra and it worked without any tearing or jumping. The 8800 has 512M of video memory opposed to the ATI Radeon HD 6870 which has 1G. Using iStat Menus 3 I found that more than 50% of the video memory is being used while WOW was running. Since the GeForce card had only 512M, I am sure it was running out.
DVD Player crashes after the card was installed. Lightroom, Photoshop CS5 and Dreamweaver all work. Windows running in VMWare also works.