I've done this before so I don't know what's wrong in this case... Maybe I have something silly wrong or I ordered the wrong thing. New iMac 27 5K with i7 and standard 8GB. Crucial 16GB kit (2X8GB). DDR4-2400 Put them in and no boot. Move them to different slots and still no boot. Removed them and of course everything is fine. Wrong memory? This is what Crucial said I should order....hmmm. Someone here up on this? Thanks, R.