Hi, I've been running 1 Dell P2715Q 4K, 1 27inch Apple Thunderbolt monitor, 1 Dell 1680x1050 monitor and a Promise Pegasus Raid away with no problems on my 10.11.2 Mac Pro (Late 2013). I'm trying to replace the 1680x1050 with another Dell P2715Q 4K. I can't get the 3 monitors to work at the same time as the promise pegasus. Meaning if I unplug the Pegasus I can get all monitors to work but if I add the Pegasus back in it doesn't. I guess I'm thinking it's a thunderbolt issue. Can someone tell me the best way to plug these into the bus to I can get the three monitors and raid array working? I've tried several different ways. Currently I'm using the Mac Pro hdmi port for 1 of the 4k monitors I thought that would help but it didn't. Any advice would be appreciated. Thanks!