Dell chromebook 11 (candy) users: How long has/did your device last(ed)?

I ask because i managed to get two Chromebooks on the cheap and subjected one to moderate to heavy use. The other has been used lightly. Now after 2 and half years of having them, it appears that the RAM is ready is quit.

I now experience Strange noises go off, random boot errors, slow processing with no new tasks, no known viruses found.

What is a normal ultrabook lifespan