Got the Samsung Pro 850 1TB working just fine. Will be returning the Crucial MX-500 in the kit. Ifixit folks, please take note and you may want to modify your kit! Also, the metal drive adapter needed drilling out two holes with an 1/8 drill. The iMac original shock-mount stubs look like they use a 6-32 screw thread not the 3mm threads in the holes. The 6-32 threads were just the right size to self-tap. So both the Crucial and Samsung SSDs were compatible with the kit’s USB 2.0 adapter, but the Crucial was not compatible on boot time with my iMac late 2009.