Why does all my ram get used up when nothing is happening?!

[Urbercharger]

So i recently had a gotten a 2x2 4GB G,skill ram sticks and i wanted to replace my old 3 gb one which had 1333 mhz , and the 4 gb one is 1600 mhz.
Ever since this my pc has been using up all my ram and slows everything down. Processor=(Amd Athon II x2 240 and MotherBoard=(M2N68-LA)

 

[gskill support]

Do you have the latest BIOS? What settings are you using? With that hardware combo, the RAM should be set to DDR3-1333 8-8-8-24 1.50V