Msi HD 7970 for Mac Pro 5,1?

Hi that would work but you will not get boot screens and it may have only the 2.5gt speed.

Try this one http://www.ebay.co.uk/itm/331065019333?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 As its preflashed for the mac pro this having proper support, speeds and the boot screens and looks like its cheaper than the one you linked to.

The card i linked to is actually as new - the seller is on this site and he writes the mods and adapts the cards so they fit within the tolerances of power and speed for the mac pro.

In terms of slower, thats dependant on whether you need an extra 3-5 fps in a specific game or not. For the most part it will be very fast indeed.

I myself am getting the one i linked to as soon as i have the money. For openCL it beats the nvidia 780 for the tasks i will do, and still it will deliver top quality and playability for my games.

I like knowing the card i will use is properly set up for my mac pro, rather than take a chance on a non-mac flashed one and risk damaging the mac.

Also the card comes with mac pro power connectors, whereas generic cards do not ( the connectors are not the same as a standard pc).

Find MacVidCards on this site and send him a pm- he can explain it better than I can