So that repair tool Samsung released to fix performance issues with its 840 EVO series of SSDs? It didn't quite do the job. The folks at Anandtech have been keeping a close eye on the issue and having seen enough reports of speed degradation appearing post-fix , hit up Samsung for clarification.
According to Anandtech's Ryan Smith, it took a few pokes of Samsung to get a statement from the company regarding the seemingly-failed repair, however, it did reply in the end. Here's the correspondence Smith received:
In October, Samsung released a tool to address a slowdown in 840 EVO Sequential Read speeds reported by a small number of users after not using their drive for an extended period of time. This tool effectively and immediately returned the drive’s performance to normal levels. We understand that some users are experiencing the slowdown again. While we continue to look into the issue, Samsung will release an updated version of the Samsung SSD Magician software in March that will include a performance restoration tool.
No additional details were provided as to why the original utility didn't make the fix stick, but the fact that it's confident of an update to the tool in March is good news. Until then, be kind to your SSD's NAND.