For a single GPU with a PCIe SSD - should I use 4790 or 5820?

I'm going to build a new game machine, but it's been a while so I looked into the SSD route for a primary drive. I'm thinking about the Plextor M.2 M6e and a (hopefully) 390X, once it's out.

All the research I did said the 4790 and 5820 were basically a wash - except for PCI lanes, which I don't understand too much about but I know the M.2 takes up some of those lanes.

Any recommendations? I play mostly battlefield, but will play the upcoming star wars game and possibly GTA5 etc.

Thanks,
Howard

For a single GPU with a PCIe SSD - should I use 4790 or 5820?