Crucial database says you may use up to 32 GB of RAM (two x 16 GB). Crucial guarantees that their RAM will work in your laptop. As for speed, according to Dell specifications, if you have a discrete graphics card then you may use 3200 MHz RAM. If you have only integrated graphics, you may use 2666 MHz RAM. If you have only integrated graphics, you might also be able to use 3200 MHz RAM, but it would run at 2666 MHz. Whenever touching components or working inside a computer, wear a grounded wrist strap, also called anti-static wrist strap, ESD wrist strap, or ground bracelet. It's a cheap and sensible precaution. Rest the laptop on an anti-static mat or at least a reasonable alternative such as corrugated cardboard. (Repeatedly touching a metal case part is not sufficient mitigation with modern components.)
hello this is my laptop i got confused for its upgrade i searched and some where they said the maximum ram is 8gb and another said its 16gb so i wanted to ask what s the maximum ram it can upgrade to and i searched my ram speed is 2666mhz but the upgrade ram in the site says the rams are 3200mhz can it hold 3200mhz or is there a ram compatible with mine.  
dell vostro 14 3000 (3400)