EXT0CB6Q for the SATA EVO and EXT42B6Q for the mSATA Evo. Those are the new versions with the fix. No info has been released if all the old versions are affected by the problem or not.
Interesting that there isn't those versions of the firmware available on Samsung's website to download other than downloading the restoration software to get it.
I decided to check the performance of my drive late last night and noticed that it was exceptional, then noticed I had rapid mode enabled. Turned it off and retested and the performance dropped through the floor, left it intending to update this morning. Tested again and it's bang on the money. Do I do it or not is the question, I'm not on the latest firmware either. Plus will using this performance tool update me to EXT0CB6Q at the same time (I'd imagine that's what it's doing anyways).
Yes it will update the firmware and there currently isn't any way to get the newest firmware without running the tool. Besides the usual back up before running it, be prepared for a long wait as it can take a while to run.
The more free space you have the quicker it will go, so if you can transfer some files over to another drive first to free up space, that should speed things up.
Drive had great speeds before in rapid mode, Updated and it now runs slower, was hitting 140k now it doesn't hit the target speed of 98k. In normal mode the speed scores were awful and that has now been corrected.
It seems the slow downs with the EVO maybe effecting the standard 840's http://techreport.com/news/27286/samsung-working-to-fix-slowdowns-on-840-series-ssd
