Problem with the 840 EVO
Apparently some problems with TLC in combination with the firmware of this drive (Samsung seems to be ready to release a new firmware around 15th of October)
Older files seem to be stored or accessed differently, whereby the read speed sometimes is as low as 40mb/s (compared to 400 - 500 mb/s). By defragging your drive (thus moving files around) the read speed is restored to the faster speeds, then slowly declining again over time (1 month or so).
See here for more info (halfway through the thread) http://www.overclock.net/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/440
Biting the hand that feeds IT
