with the latest APU 7850k, what you want is not faster ram but lower CAS, and you only want Dual channel, (no quad channel support from AMD yet, sigh), AMD loves lower CAS count! as it is, according to sources anything over 2133Mhz is a waste, they don't have the support for it (i think) better to get 2133Mhz with a CAS of 9, AMD=wants lower CAS, Intel=Want more Mhz! from what i have read! and if you want abit more power for cheap, just go a dual Graphics the 7850k Crossfires with R7 240 and 250, best to get the Gddr5 versions!
or if you want it setup for future
also if you can afford the extra cash, go for the A10-7xxx all depends on how much you have budgeted and what mobo you are getting too and whether you are getting a case (also its form factor), best to look here to get a rough idea of what you will be spending.
heres an example of a caseless build (if you already have a valid case) its a Micro ATX build, i myself prefer Full ATX's (being Aussie i love my shizz big) http://uk.pcpartpicker.com/p/3iifI
if you can afford the extra i would go for either http://uk.pcpartpicker.com/part/asrock-motherboard-fm2a88xextreme6
they are better boards and allow crossfire for more cards!