here is some info to back up the idea that even even crucial suggest that trim being on is good idea and anandtech say you should run with trim on for the M4 even though it has garbage collection, I got this info from another site :
apple support forums M4 trim discussion post
in the above forum post it references two articles below about crucial SSD’s and whether garbage collection is sufficient, the jist of it is, in the crucial c300 and M4’s ssd drives case it is worth running the drive with trim on.
crucial forum post 1
crucial forum post 2
and an anandtech article clearly stating that the crucial M4 needs an os with trim support to make sure that performance doesn’t degrade long term, with performance metrics to back it up.
and if you need help in enabling trim i recommend to enable trim using this method :
if anybody is finding that there trim support got disabled in 10.8.3 12D78 or the instructions to enable trim didn’t work with their ssd on ML 10.8.3 12D78, then I recommend having a look at this python patcher,
python trim patcher & instructions
but bear in mind its not for amateurs or the faint hearted, but it worked for me in getting trim support enabled on a crucial M4 128gb drive when the terminal commands in this article didn’t work. place the python file in root and sudo run it with the apply argument as noted in the instructions and bear in mind instruction get the python.py file name wrong compared to that in the zip so you will have to be aware of this and correct for it. please read the instructions etc.
if you have got trim enabled a while after the SSD has been in use ? and what to clear freespace on the SSD to ensure that trim and Garbage collection is done, then >
“You can do it by booting into single user mode (CMD + s) and then typing fsck -ffy at the root prompt and it will erase all free spec and prep for TRIM.”
once the fsck command has worked enter
reboot
to restart the computer, and a fuller explanation re fsck process here why apple has decided to remove the erase free space option for SSD’s i have no idea ? except they presume TRIM has been on since install, although I know of plenty of users who have apple SSD from purchase that claim they have come with trim OFF, so i’m not sure thats a valid reason to take this option from the GUI user ?
not at the point of needing to enable trim … as you have yet installed one ? Need a guide to install an SSD in a mid 2011 imac ?
click on the link below ?
if you need the best/simplest and cheapest method to install an ssd in your imac mid 2011, I recommend the best ive found by toby guide here