Ah, it's a curse but I have to keep FCP7 going for some clients even though I'm organising to update my Mac Pro (6 core, 3.3mhz 2010, 24gb RAM, GPU ATI Radeon HD 5870) and move to Resolve/FCPX. So my plan is to preserve the old system completely as is (OS 10.8.6) on a separate drive and instal El Capitan on new drive and switch back to the older system if I have to use the Final Cut Studio (I've heard it opens and works in El Capitan but don't want to rely on this). But if I replace the old graphics card with something much faster like the Nvidia GTX 980TI, will the old system start up? I don't have space to have 2 graphics cards in the PCI slots but the 980 will only work with the more recent OS. Or is it that it will work but it won't go as fast as in a newer system?