use ram vendor ram test tool like crucial memory advisor. some laptops can use faster ram some cant due to the cpu and or chipset used on the mb. in real world 1600 speed ram base speed is 800*2. and 1333 is 6xx. so there no real like help going with 1600 ram unless it cheaper and easer to get then the slower ram. with laptops you have to find out if the ram is on the system board or in a ram slot. if it on a ram slot it be cheaper to get another dimm of the same size to 2x the ram if there two ram slots on the laptop. if you go with faster ram you want to use a set of ram to fill both slots to get the fastest speed from the laptop memory controller.