Some more users have confirmed that their 840 EVOs are still bugged even with the last firmware fix. Even PCPerspective has confirmed that they too are seeing the same issues.
Samsung 840 EVO Performance Restoring Firmware Only Partially Effective
Samsung… you tried to fix this problem before with a firmware fix, obviously it didn’t work. At this point, we the owners of these SSDs call upon Samsung to do the right thing. Replace these SSDs!
Sign the Samsung 840 EVO Replacement Petition and make Samsung right this mistake!