Lightnings do really tame the beast in regards to the 290x, but the 3 slot cooler does leave issues for crossfire, i would love a second, but it would mean new MB and prob CPU. I think most of us would have problems and be putting the second into the x4 slot in crossfire. When the 390x lightning comes out, I will study very carefully the right combinations of hardware.
could always use a riser cable like I did.