my laptop name is toshiba satellite c665- p5012.. and current ram is 2gb ddr3 1066 mhz, is it compatible with 4gb ddr3 1600 mhz????.. don't know about the singl channel or dual channel..
I'm not an expert on this type of thing, as I deal more in Linux Support, but I wanted to at least point you in the right direction. A web search led me to this post, which might give you some good information:
I hope that helps!