You'll get many, many, many years of normal use out of an SSD without bumping into its write-cycle cap — especially if you're storing basic media and productivity files on a mechanical hard drive. And even if you're not doing that, you're probably more likely to buy new hardware long before your SSD packs it in.
You could achieve fewer writes by not saving temporary files to your SSD — for example, you could redirect your browser cache and PhotoShop scratch disk to a mechanical hard drive — but this will lead to slower performance when your system needs to access these files. You're probably better off sucking it up and accepting the greater amount of writes for the increased performance.
DON'T defrag your SSD!
You shouldn't defragment an SSD. Period. Shuffling all those bits around on an SSD won't improve performance like it will on a mechanical hard disk, but it will generate many extra writes that will reduce the lifespan of the drive.
Modern defragmentation tools and operating systems should refuse to defragment a solid-state drive. However, old defragmentation programs may not know the difference and may happily defragment an SSD. Don't let them!
DO let TRIM run wild
TRIM, however, is essential for keeping your SSD in tip-top shape.
When writing data, the SSD can write only to empty sectors. This means if an SSD needs to modify a filled sector, it has to read it, note the contents, modify them, erase the sector, and write the modified contents. If we wanted to overwrite a sector, we'd have to erase the sector and write the new contents to the now-empty sector. The extra steps take time.
Operating systems typically just delete a file by marking its data on the disk as deleted and erasing the pointer to it. The file's data is still there on the disk, but it will be overwritten only when the operating system needs that "empty" space to write new files to the disk.
The TRIM command tells the SSD to erase and consolidate cells that are no longer in use, so writing to those sectors in the future will be just as fast as when the drive was new. If not for TRIM, writes would take longer, and an SSD's performance would deteriorate as you filled it up and deleted files from it.
Windows 7 and onward has had TRIM enabled by default, so there's nothing special you need to do if your PC is using one of these newer OSes. TRIM won't work on Windows Vista or Windows XP (you've upgraded from XP, right?). You'll need to use third-party SSD management software (like Samsung's SSD Magician or Intel's SSD Optimizer tools) to force TRIM on those operating systems, or the trick outlined in PCWorld's guide to restoring an SSD to peak performance.
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