The E5450 requires DDR3L -- you cannot use DDR3 in it. Older systems could take either -- yours cannot.
 Hello. I am doing this on a Dell Latitude E5450. It currently has one stick of 8GB, pc3l(ddr3l) RAM made by SK Hynix in slot 1. I dug a piece of ram out of my old computer, a dell latitude E6330. The second ram is a 4GB stick, pc3(ddr3), made by Samsung. When I put the second stick into the other slot and tried to turn my computer on it tried to boot. The fan came on, some lights came on, but then it died. Any help? 
Dell Latitude new RAM not working