Hey everybody. I'm new to the forum and I was wondering if I could get some advice regarding a Gigabyte 2GB Graphics Card in a 2006 Mac Pro (2.66 Dual Dual Core Xeon, 4GB Ram) After doing some research in regards to a "supported graphics card" for a Mac Pro hacked into Mavericks 10.9.4 using Tiamo's boot.efi, I opted for a Gigabyte GT640. I was informed that the GT640 was plug and play for Mavericks, bar the boot screen, and everything would be alright. However, after installing Mavericks on my Mac Pro, I found that the GT640 would not output any signal to my monitor, which runs off VGA. I installed the old 7300GT in Slot 4 (the GT640 is in slot 1), which is unsupported and runs sluggishly, and it powered the display okay. I checked the System Report and it recognised both the GT640 and the 7300GT. Also, I found that although some apps like Safari and Quicktime demonstrated flickering and graphics tearing because I was powering the display off the 7300GT, other apps such as Firefox and Motion ran perfectly fine. I installed DaVinci Resolve Lite and it recognised the GT640. I thought it might have been an issue with the VGA port, so I purchased a VGA to DVI-D adapter, but still I am having no success. I have also tried switching between the NVIDIA drivers and the OS X drivers, which also did not work. Not sure if anybody had any ideas or has had the same issue. Thanks for your time!