OS X 10.10.4 Now Supports 'TRIM' for 3rd-party SSDs
OWC SSDs do NOT need TRIM (MPG has never used or enabled it all these years).
See OWC SSDs Built to Perform with or without ‘Trimforce’ Command.
To enable TRIM for your SSD, use Terminal (in the Utilities folder). Regrettably, there is no way to control the behavior on a per-SSD basis. Given the claimed risks this is a dubious design (it’s on for all non-Apple SSDs, or off for all).
MPG strongly recommends backing up before enabling TRIM.
Devices connected indirectly, such as multi-protocol enclosures with multi-port chipsets might not be accessible in a manner that supports TRIM.
The command to enter in Terminal is trimforce enable.
diglloydMP:DIGLLOYD lloyd$ trimforce enable
Man entry for trimforce
TRIMFORCE(8) BSD System Manager's Manual TRIMFORCE(8)
trimforce -- enable TRIM commands on third-party drives
trimforce enables sending TRIM commands to third-party drives attached to an AHCI controller. By default, TRIM commands are not sent to third-party drives. Use extreme caution when enabling TRIM, as some drives may not correctly handle the commands. trimforce must be run by the system administrator.
Start sending TRIM commands to AHCI-attached third-party drives. Requires a reboot to take effect.
Stop sending TRIM commands to AHCI-attached third-party drives. Requires a reboot to take effect.
Display brief usage syntax.
trimforce will exit with status 0 if successful, or with an appropriate error if it cannot parse input, allocate memory, or is unauthorized to perform its work.
The trimforce utility first appeared in OS X 10.10.4.