If you already have 8GBs of DDR3-1333MHz and you add 8GBs of DDR3-1600MHz, the 16GBs RAM would all run at 1333MHz. Bottomline, it may or may not run at all with the higher speed RAM.
Do you actually know what RAM is in it now ? (NOTE...it may be equal to or greater than what the mfg advertises.)
I am trying to buy new RAM for my gateway desktop and there is a really good deal on for some DDR3 1600MHz RAM. The memory adviser results on the crucial website say that my computer can hold 16GB of 1333MHz DDR3 (http://www.crucial.com/store/listparts.aspx?model=FX6831-01&Cat=RAM). But does that mean that my computer can't handle 1600MHz RAM? And would there be a performance difference if i was to have 1600MHz instead of the 1333MHz? Also, does it matter if the RAM is DRAM or SDRAM?