overclocking ddr3 ram

[actionstan]

im currently running a set of gskill ripjaws at 7-8-7-24 1t 1600 mhz with 1.6 volts... i would like to overclock these a bit as i think i would see at least a slight gain in some stuff.. but i have no idea what volts are safe to put into a ddr3 module as i dont want to risk frying them because then i would be sad.. so if someone could give me a ideal safe voltage for modules like these that would be great.. im hoping to overclock them maybe to 1800 mhz with similar settings thanks! if you dont think its worth overclocking these modules let me know, and for overclock testing which is the best software.. i know memtest is good but it takes a while to run and id like something that could stress it a tad faster thanks!