I jumped ship from SATAs to M.2 a month ago with a new computer and to quickly sum up the situation with Samsung 960 Pro from own experience and hundred page long threads on official product forum:
- last published firmware on website is 2 (don't know the long number now, writing from phone)
- a version 3 was released, system freezing started occurring in some cases and some people even ended up with bricked drives (in relation to eDrive IIRC)
- bricked drives could be reportedly used again after PSID revert, but Samsung consistently refuses to release the tool (other manufacturers do and the tool is also useful for recovering drive with lost OPAL password)
- firmware 4 reportedly exists, which can be obtained through Magician (Samsung's tool for SSD) and should solve problems from version 3. Conflicting reports on performance.
The craziest stuff is that:
- Magician will now tell you there is a new firmware for your drive, but it won't tell you with which version is it going to "enrich" your shiny new drive. Will I get 3? Or 4? Especially when only 2 is posted on the Samsung's page!
- firmware changelogs are kept secred, just install this for no reason
- no downgrades are possible
Worse than X25-M password bug. You have to be scavenging official forums for information that should be posted with the firmware and be cursing at/begging moderators to reveal some more. Ah and reportedly there is some mysterious incompatibility with major BIOS vendors in regard to eDrive. No, they won't tell what the bug is, nor on what boards.
Also, custom OPAL PBAs (image flashed to special unlocked area on disk for booting with disk locked down) don't boot in current desktop boards. Might be non-Samsung issue, maybe the one mentioned above.
How does this stuff work together at all?
The capacitors needs to be reliable, small form factor and hold enough charge to keep the controller, DRAM and NAND powered for a minimum of 15-30ms. 10 years ago what was available was not so great but now the options are much better.