I have a 2017 iMac that I put a new SSD in 5 years ago. In the past 2 years it's began starting sporadically, but always starts after I run it in Recovery mode (Command+R). When I open Disk Utility the main Hard drive is not visible, even after selecting "All devices". It doesn't see the new hard drive and I understand this is because the original software only recognizes the original hard drive. I've read that I can buy an external hard drive (Samsung SSD portable T2) and set the mac up to look at that hard drive to start and run it. I'm wondering if it's worth the investment? Everything else works great on this iMac. It runs fine without any glitches. The only problem is the start up. I back everything up on it with Time Machine, so no problem there. Any advice would be helpful.   submitted by   /u/DitheryDo   to   r/mac [link]   [comments]