matt798 :
the advantage of having 2 sticks of ram is that the system will reserve 1 stick for the system and the other for programs.
some memory manufactures have urged toms hardware in performance testing to use 4 2gb sticks.
so it can said that 2 4gb sticks is needed for best performance and stability overtime even if 2gb never get used 99.8% of the time but having that extra usage at hand to the average consumer allows for a performance standard to be set.
currently pc3 drr3 1600mhz cas 9
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Sorry but No, A) the system doesn't reserve 1 stick of DRAM for itself and B) using 4x2GB sticks is more stress on the MC (memory controller) than two sticks, so you don't want to add unneeded stress.
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To the original question, it will be up to the developers - 3 years from now (or even sooner) I'm guessing 16GB will be the entry level for desktops, just a couple years ago everyone was saying 4GB is more than anyone will use, 2 years before that they were saying the same about 2GB and with DDR4 on the horizon, think 16GB will soon be the starting point, plus as BF4 has shown, they are starting to utilize DRAM more and more in games