Pjr_cdf,   Normally the systems are 5 years from ship date. So the earliest M630's shipped will approach End of Life around the end of 2019, but this is all based on parts availability so there isn't a hard End of Life date, it is all based on when parts are getting to be exhausted.  Let me know if this helps. 
Can anyone advise on the end of life date for the PowerEdge M630?
End of Life for PowerEdge M630