The latest fix for the read-speed-slowdowns dogging Samsung's 840 EVO SSD is now out—sort of. Version 4.6 of Samsung's Magician software is available for download on the company's site, but only in limited quantities. According to the error message that pops up when I click through, "there is a daily limit on the number of Magician 4.6 downloads" until April 27.
PC Perspective notes that several other sites have mirrored the software already, and that those downloads are identical to the one provided by Samsung. There's another catch, though. The "Advanced Performance Optimization" tool designed to restore old data to full speed requires updated firmware that doesn't seem to be available. Samsung's download page only lists old firmware revisions, and the Magician software's built-in updater has nothing for the drives I've got in the lab. PC Perspective suggests Samsung's firmware server may be swamped at the moment. Restarting the Magician software is supposed to help, but it hasn't worked for me yet.
The updated firmware should have the periodic refresh feature designed to prevent further slowdowns in active systems. That mechanism can't prevent performance degradation on unpowered drives, but it's unclear how long it takes the problem to manifest. I'm still waiting for Samsung to clarify a few details about the refresh routine, including how frequently data is rewritten.
Given the window for the download limit, a wider release seems to be planned for the 27th or 28th. Samsung may be rolling out the new fix slowly to ensure there are no problems with the first wave of updates. That's not a bad idea given the drive's popularity—and the fact that this is the company's second attempt at a fix.