I'm using this GTX 980 in a 12 core Mac Pro aluminum tower. I'm using it primarily for 3D work in Maya and compositing in After Effects. This card is replacing an old Quadro from about 2010. I'm quite pleased with the IPR real time rendering using VRay 3.4 in Maya, and the compositing in AE is probably about the same, but I am using my old, own it forever CS5.5, so newer versions might take more advantage of the card's horsepower.
This is a flashed ROM card, but there are only minor glitches now and then, and nothing that causes problem. It's mostly when changing screen resolutions or quitting VRAM hungry apps. At those times I will often see momentary flashes of whatever is sitting in VRAM before the card updates the memory allocation. Other than that, smooth sailing. Quite happy with the purchase.