why noone use cheap brand such as plextor like me ... i guess this brand can easily break

Ok thanks, asides from enabling AHCI and asking Bios to boot straight from SSD, is there anything else I need to do?

as in how should i disable defragmentation, etc

Using Samsung test on competition drive can be biased. Use Crystaldiskmark or AS SSD.

Did you ever enable TRIM command after you install Windows?

*By default it should be enabled, but there are times it can be disabled due to other components.

Ssd performance will degrade over time, especially the used capacity is over 50%. Over provisioning and sufficient time for garbage collection can help but eventually you will need to do a secure erase once in a while to get back the speed.

no. all ssds have this because this is about how nand flash works.

when a file is deleted, the process doesn't delete all the file data. there will be partially filled blocks that are not cleaned. note that the trim command only ask ssd to remove file data when it's deleted, but it doesn't force the cleanup operation to these partially filled blocks. to mitigate the issue, garbage collection is used to do this, by looking for partially filled blocks in the ssd, and clearing them to make free space. over provisioning is also important i this case to prevent performance degradation, by giving free space to the controller to do gc.

usually secure erase will reset everything to the factory state. (well, close to i should say)

Scrap the first one off...  The drive has a yet to be fixed read speed bug (even though a fix by Samsung is applied)....
Though my 840 EVOs have yet to see any slowdowns...

The Intel 530 would be my choice, or if you really have the cash to burn, the 840 PRO/850 EVO would be my choice.

Sandforce controller, and the reason is becos of?

oh that's bad. can you share with us your usage? also, did you do op? how many % of the total space for op if you have done that? did you do other ssd optimizations? did you use ram disk or ram cache? i wonder why no one has expressed this short-life problem before. i am using 2x plextor m5pro xtreme for 2 years plus, 512gb, latest firmware, 15% op. no issues. i suspect system setup and usage contribute to the problem, but you will never know.

of your 3 choices, intel 530 is a good buy because of its longer warranty period. crucial m550 is newer.

Tell us or better show us. Much better to learn from a person than a review website. Tell Tell Tell

sorry i shouldn't refer your case as 'short-life', i should say 'speed-drop'. op is over provisioning, putting certain amount of unallocated free space at the end of your ssd. if you relocated your temp folders and web cache to it, this method saves a lot of writes to the ssd. yes it doesn't affect ssd's read speed.

based on this review (http://www.anandtech.com/print/6090/plextor-m5s-256gb-review), the gc part should be fine for m5s. by the way your ssd is actually still very healthy based on the total writes (if compared to tbw of 72tb). one last thing, did you swap sata port before? it looks like a sata 2 speed.

yeah it's sata ii speed. one more thing to check is the sata cable.

do you made any bios update? or maybe you can check the sata setting in bios.. also you can try update to the latest chipset..

i think he's using the right one. because the speed drop was said to only occur recently.

why only 120GB? should take 250GB ma.