16 seconds is nothing for a desktop. There is a lot going on there. 6 seconds are delays that are intentioanal to give you time to recover from a bad OC.
Disable CSM will help some if you have it enabled as some of that time is spent looking for a boot sector on your spinner HDD.
Personally, I dont sweat boot times so long as its reasonable. 16 secs is
VERY reasonable, especially for a desktop!
“Two things are infinite: the universe and human stupidity, I'm not sure about the former” ~ Albert Einstein