Q: Two issues: iMac randomly reboots after watching Netflix, and left fan randomly turns on

Two issues: iMac goes into kernel panic and reboots after watching Netflix in HD, and left cooling fan randomly starts. Is this RAM or logic board?

Specs:

Model Name:          iMac

  Model Identifier:          iMac12,2

  Processor Name:          Intel Core i5

  Processor Speed:          3.1 GHz

  Number of Processors:          1

  Total Number of Cores:          4

  L2 Cache (per Core):          256 KB

  L3 Cache:          6 MB

  Memory:          20 GB

  Boot ROM Version:          IM121.0047.B1F

  SMC Version (system):          1.72f2

The fan issue has been there for a while, but the kernel panics, AKA crash and reboots started after I got new Crucial RAM for the 2nd time (returned and replaced the two 8GB sticks, because the crashes were worse).  Are the chances that I got 2nd batch of RAM likely, or is there logic board issue here?