For gaming - Not see a difference with either - 8 Gigs is pretty much the sweetspot and higher speed maybe 1->2 FPS faster if that.
For rendering the higher quanity will probably make a bigger impact.
Generally:
... Very little performance gain going from DDR3-1600 -> DDR3-2400 with the exception of a few specialized apps.
.. For >8 gigs also dependent on apps, but some rendering programs and Photo editing programs will use as much ram as you can throw at it.
.. For Intel IB CPU,using ram above DDR3-1600 Voids the Intel CPU warrantee - If OCing not relavent as OC voids the warantee anyway.