I was pretty happily running 5 1080p clients on an i7-2600k @3.6GHz with a 580GTX Ti until I blew up my motherboard a few weeks ago. I had to drop some settings to keep FPS up with the main client at High graphics options but it worked just fine. I'm guessing that would have held up for Legion as well, with some further reduction of graphics options to compensate. 16GB of RAM might not be enough for Legion, depending on what you're doing on that machine while you're boxing.