This unit is a prototype GPU manufactured by ATI as a sample card for evaluation by Apple. Both ATI and Nvidia built samples like this to present to Apple in order to try and win the contract to produce their GPUs, but ultimately Nvidia won on this card and produced the GT120 (very similar in aesthetics to this card but much thinner and smaller) which was used in the 2009 Mac Pros. This card represents ATI’s sample, one that never got to market and was only built for evaluation purposes. This card was tested in a windows machine to no avail, but it was only intended for Mac Pros so this is not a surprise. The previous owner tested it in a Mac Pro and it did output graphics, but had a checkerboard pattern on the screen and prevented boot past the Apple logo screen. This is sold as parts/not working, but this is really only for collectors and not anyone actually wanting a GPU to use. Side note: I removed a piece on the card to get photos and a spring popped out. It is obvious how the spring fits into the holes, however seems to be impossible to re-bend into it’s previous orientation as it was probably done with a machine originally. I tried for a bit but gave up- Perhaps you’ll have better luck!