iMac Late 2015 - internal SSD - install MacOS before installation?

[Renko31]

Hoping for some advice from all the cleaver bods on here

I have a Late 2015 iMac. The Fusion drive failed and after a quote of £950.00 from an Apple specialist to fix it (which I declined), I have decided to try doing myself.

I've a got a 2.5" SSD and a kit to do the replacement, but should I install MacOS on the drive before I install it, or wait until the drive is installed and then install MacOS?

Any help appreciated.

 

[DeltaMac]

There will be no real difference installing the system before or after installing the SSD

However, I have sometimes seen internal drives that fail so badly that the Mac won't boot properly until the failed internal drive is removed, or at least disconnected. And, if you are disconnecting the old drive, then you are most likely at the point where you could simply install the replacement SSD.
And, unless you are certain about which device has failed, I think you should remove both devices, not just the one drive where you will install the new SSD.

 

[Renko31]

Thanks DeltaMac

I was going to remove both parts of the Fusion drive as I had boot up issues with both of them before the HDD finally failed completely - so that fits with your experience.

Cheers

 

[DeltaMac]

Just curious - Are you planning to replace the SATA hard drive, or the (much faster) PCIe/m.2 card?
(cheap Sintech adapter card so you can use "normal" NVMe cards, you don't need the more-expensive PCIe cards with the Apple proprietary connector. I try to mention that with try kind of upgrades. )

 

[Renko31]

I'd already got a SATA drive because I'd heard he NVMe cards were proprietary
Oh well - I'll know for the future!

 

[DeltaMac]

I'd already got a SATA drive because I'd heard he NVMe cards were proprietary
Oh well - I'll know for the future!

Yes, you are correct. The drive card that comes installed on your Mac has a proprietary connector. But, you CAN use other "normal" NVMe cards, with an adapter. The adapters are easy to find, less than $20, and work great -- with your choice of drive. note: there are a few cards that are not compatible with the adapter to use in a Mac, but that information comes with the adapter...