I had several SSDs ( a 1TB 840 evo and a 512gb 840 pro ) that I wasn't using as I had always used them for my main drive or gaming installation drive, never as bulk storage. But as I decided to delete a bunch of crap on my 2TB mechanical drive and could easily split the backup stuff onto those 2 SSDs I got rid off the optical drive, removed the drive cage and extra sata power and data cables to clean up the case. Now I only have my 950 pro, and the 2 sata SSDs, and will soon have another M.2 drive, possibly waiting for the 970 pro. My only way to judge the SSD speed has been how snappy the O.S feels and game load time, neither of which can really be compared to anything because load time for a game save or level etc always varies depending on whats going on and the game. But I copied the files from my optical drive to the spare space on one of the SSDs and then took the optical drive out anjd copied the files to the other SSD to stay. I was getting maybe 88-100mb going from ther mechanical to the SSD, and around 300 avg 400 mag from SSD to SSD. This is the first time I've ever had a qualitative way to see how limiting an mechanical drive is, because it was the same files, several hundred gig, mixed file size, and I saw the comparison right afterwards. When installing games it's not like you do it as a benchmark, and then uninstall and install on another drive to see the difference, so I never saw the real world difference, only the perception of O.S responsiveness and game loading that is a bit faster. There is no way I will ever use another mechanical drive after that,l not when you can use any old SSD for some of your file backups. That SSD is from 2012 and was 200% faster at a minimum. Plus my case is clutter free now without the cage,l drive and cables.