I bought a Samsung SSD 850 EVO 250GB for my MacBook Pro 13'' Early 2011, but am unable to install OS X to it. (Yosemite 10.10.3) When installing the SSD internally, OS X doesn't find the drive, and diskutil reports the following (tested with Internet Recovery, old install on external drive and own thumb drive installer): Code: /dev/disk0 #: TYPE NAME SIZE IDENTIFIER 0: FDisk_partition_scheme *250.1 GB disk0 1: 0xEE 250.1 GB disk0s1 However, when attaching the SSD via USB (externally) the following is reported by diskutil on the same machine: Code: /dev/disk0 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *250.1 GB disk0 1: EFI EFI 209.7 MB disk0s1 2: Apple_HFS SSD 249.7 GB disk0s2 Partitioning didn't work, hangs on "Waiting for volumes to reappear…". After installing OS X on the SSD while attached via USB and reinstalling internally, drive is not found again. The old HDD works fine internally, but is very slow (constant beach balls, more that when used externally) and has a negotiated link speed of SATA 1.5 Gbps. Any ideas? SATA cable broken? Chipset broken? Thank you for your help!