I'm looking to buy a Nvidia Titan X Maxwell second hand. It has previously been used for gaming and productivity software. What sort of life could I expect from such a card?
It is a gtx1070 level GPU, so it will keep up with most apps for a couple of years. Its life span depends on when it was bought, how often it was being used and if there is still a warranty.
A certain amount of it is luck, but if its had an easy clean life then it should carry on for many years.
I know of plenty of gtx 500 and 600 series that are still running fine at 6-8 years old, and to be honest at that age its not a big deal if it fails as the performance level is so cheap.