2010 MAC PRO 5,1 VIDEO CARD WITH SIERRA

Are you definitely going to keep your mac on macOS Sierra, if so you do not need a 'Metal' capable graphics card.

'Metal' capable graphics cards are only required if you are considering upgrading your MacPro to macOS Mojave.

Also remember that only Mac Edition or 'flashed' for Mac cards will give you boot up screens and access to the Startup Manager.

You can install PC cards in your mac (they are cheaper) but you will not get the boot up screens or the Startup Manager, so keep your factory installed graphics card handy in case you need it at some point.

Your MacPro can also be upgraded to macOS High Sierra, which is still receiving Security Upgrades, at the moment.

How to upgrade to macOS High Sierra - Apple Support

Before upgrading make a full back up of your Mac.

Check that third party apps you use have updates available for the new OS.

https://roaringapps.com

Check that your printers/ scanners etc have updated drivers and software available for the new OS.

Hello,

You will want to get a graphics card that supports Apple’s Metal. Here are some options however this document has not been updated in a year so there may be others out there. I highly encourage you to do your own research for Metal compatible graphics cards as those will be fully supported on Macintosh.

Install macOS 10.14 Mojave on Mac Pro (Mid 2010) and Mac Pro (Mid 2012) - Apple Support

Yes so if you're going to be using Mojave either in an internal drive or on an external drive you will need to look for graphics cards that are Metal capable, so click on the link that Quickpost posters in the first reply. I use an Nvidia GTX 680 in my MacPro, but they are getting rare and quite expensive.