Considering upgrading HDD in 27" iMac

[Poncho]

Ok, thank you for all the suggestions. In the end I decided to buy a fast external SSD

That's exactly what I have done with a 3TB Fusion iMac from the very same year. I now boot from a Samsung X5.

 

[Juicy Box]

I now boot from a Samsung X5.

I have been booting from a Samsung X5 for a few months now on my Late 2012 iMac, and it has been doing fine.

I know that some have reported throttling of the X5 due to heat. Not necessarily overheating, but the thermal protection threshold is set too low, and it may throttle down about to USB2 speeds.

Have you experienced this using it as a boot drive? I personally have not, but using it on my Late 2012, I never come close to the high speeds (and hot temps) that it is capable of.

 

[Poncho]

Have you experienced this using it as a boot drive? I personally have not, but using it on my Late 2012, I never come close to the high speeds (and hot temps) that it is capable of.

Not at all, apart from the initial Carbon Copy Clone of my internal Fusion Drive to the Samsung X5 when it got a bit hot. Otherwise it runs like a speedy internal drive within normal temps as shown by DriveDX. The only issue I have had, twice, is that my iMac has had a 'wake from sleep' issue, whereby I am presented with a black screen and non-responsive keyboard and mouse and have to press the power button at which point the iMac re-boots and says there was a 'Wake From Sleep' failure (or something along those lines). Could well be to do with my using the X5 as a boot drive (or perhaps not). Haven't got round to re-setting/checking VRAM/PRAM etc. Or I could just click 'Prevent computer from sleeping...' in System Preferences/Energy Saver. But I will investigate when I have time and should the issue present itself again. But overall more than happy.