Mid 2011 21.5 inch iMac shuts off randomly and SMC reset doesn't fix it. | MacRumors Forums
What to do when your iMac won't turn on?
Scored this iMac late 2009 for free, the person who gave me it thought it had a graphics issue, one pram reset and software update later, it works great! : r/mac
nvram reset bug - Apple Community
SMC resetten op MacBook en iMac: waarom en hoe?
How To: Reset the SMC (System Management Controller)
What to do when your iMac won't turn on?
How to Reset SMC, PRAM, and NVRAM on Mac?
NVRAM en PRAM van een Mac herstellen bij problemen - appletips
How to Reset Mac NVRAM, SMC, or PRAM
How to Reset your Mac or MacBook's PRAM and SMC | Avast