Recommendations for SSD drive for late 2013 iMac 21.5"

I am considering two drive replacement kits from OWC, namely the OWC Mercury Extreme Pro 6G ($202 CAD) and the OWC Mercury Electra 6G ($160).

Does anyone have any advice on which of these two drives would be best, or other SSD recommendations?

Yes. The Mercury Extreme Pro is the better of the two options, if for no other reason it has a longer warranty. Those are the only SSDs I have used and can personally recommend. The Electra is probably ok too but I just don't happen to have any of them.

My oldest Mac with the Mercury Extreme Pro is now over fifteen years old and is still in occasional use. It works great.

Another question: Once I have swapped out the drive, can I continue using my existing external drives used for Time Machine backups (G Drive Mini and G Drive Mobile) ...

Yes. You will need to re-select the existing backup. When asked if you would like to continue using it to back up that Mac, answer in the affirmative. After a long time examining the existing backup TM will pick up where it left off.

However, after replacing the startup drive you would be better off immediately restoring that Mac from the existing backup rather than installing macOS anew and using MA. That ought to be straightforward: Restore your Mac - Apple Support, but if something doesn't go as expected please write back. For example your existing macOS version may be a factor.

... or will these need to be reformatted and TM backups started from scratch?

No.

Adapters cost about $2 so that cannot be a real reason. However the computer is yours and if you want to upgrade it well okay. However, by doing so you will find that you are painting yourself into a corner as updates for obsolete versions of Mac OS and Browsers may make your third party software incompatible at some point. We see this all the time with other users, who want to extend the life out of their obsolete computers.

Also, there is no reason to spend $1800-2000 on a new computer when you can buy an Apple refurbished Mac Mini for as low as $509, add $100 for a display and you have a FAR more powerful device than your 2013 iMac that has a full 1 year warranty and is eligible for AppleCare none of which is available on a 2013 iMac! In short, your argument has been heard however I don't believe you have a good idea of what is available to you. For less than $1000 you can have a VERY nice Mac mini that is far more advanced than your 2013 iMac will ever have the hope to be.

Again, the decision is yours but at least go into it by doing your due diligence before you spend any money.

By the way, if you are not aware of Apple's refurbished program, simply go to www.apple.com, scroll to the bottom of the page and click the Refurbished store. There is no downside to an Apple refurb, they are current models, identical to new and as mentioned have the same warranty as any brand new Apple product.

Also, Apple will recycle your 2013 machine for you at no charge.

Great! Thanks for the update. You extended that Mac's life by at least a couple more years at minimal cost.

SSDs are terrific. You may have lucked out by getting an OWC Extreme Pro 6G that was simply relabeled as an Electra for whatever reason OWC may have had for doing that. I think all you'd be missing is the Extreme's five year warranty vs. the Electra's three years. There is very little quantifiable performance difference between them, and probably no perceivable performance difference at all. Either one is a quantum leap over any spinning hard disk drive.

The main difference between the Extreme and the Electra is that the Extreme mentions:

• No slow downs - Maintains read/write speeds exceeding 500MB/s over the entire drive capacity.

Personally I would go for the Extreme just to have this regardless. I know these OWC SSD have changed somewhat over the years by now utilizing different TLC NAND & a different SSD controller which affects performance. SSDs implement a write cache to help make the SSD seem fast when using TLC NAND so as long as your writing of data doesn't exceed the SSD's write cache, then the SSD will perform fine. The Extreme must either use a slightly different method of implementing the write cache than the Electra, or the write cache is much larger in order to claim no slow downs with the Extreme.

However, as long as you are not writing multiple GBs of data to the SSD for 30 seconds or more during your normal workloads, then the Electra should probably be fine. It has been a while since I tested or used one of the newer Mercury Electra SSDs.

Those would be good choices for an SSD, if the installation seems beyond you...

https://ca.macsales.com/installvideos

Then an external SSD might be a future proof solution, but not as fast of coarse...

https://ca.macsales.com/item/OWC/ENVPMCA02/

USB2 speed...

I would get an external SSD and clone your boot drive to it with Carbon Copy Cloner . Then boot and run from it.

As for drives the economical route would be to get a bare SSD (I recommend OWC -MacSales.com) and a SATA to USB adaptor like this:

If you'd rather have an enclosed SSD call OWC's Customer Support and see what they recommend for your Mac model, work requirements and budget. They have several.

With the above setup I'm able to get Read & Write speeds of about 450 Mbs. I use it to boot into older systems with my 2017 iMac to run older software occasionally.

Just some more food for thought.

Regarding a "clean install" vs an "upgrade install": I have performed the latter on all my Macs that get replaced, since the 1990s or so.

It might not make as much difference today as it did in the past, but the advantage of restoring from a TM backup results in the exact same user experience that you're probably used to having. Same preferences / settings, same printer drivers, same appearance, same everything — to the extent possible. Programs that don't work might get a "prohibitory symbol" or are otherwise relegated to an appropriate folder to be disposed of at your convenience.

That also means I might come across some moribund 68000 code which has not functioned since the early 2000s but it's essentially inert. When I find those files I just drag them to the Trash.

In your case restoring from TM should also retain licensing codes, etc that might otherwise be difficult to find. Of course that won't apply to App Store purchases which is the way things are headed.

If none of those factors concern you then it really makes no difference. And, as I wrote it's less of a concern as time goes on. But that's how I installed the OWC SSDs, so draw your own conclusions. They have performed far beyond their warranty periods and continue to exceed my expectations.

I have not had any Macs with spinning hard disks for at least a decade now, and don't miss them a bit.

+1, replace the 2013 with a new Mac. It simply does not make any sense to spend $1 or more on a machine that is obsolete. If you are in the US or other participating countries you can buy new, an Apple refurbished Mac, or buy used from a reputable reseller such as macsales.com.

+2 Don't do an internal SSD upgrade.

Startup and run from an external 1T USB 3.0 SSD instead.

see > Use an external SSD as your startup disk … - Apple Community

Honestly, it’s going to cost you more for an SSD than that machine is worth. You’re better off buying a new Mac. That one is obsolete.

It just takes longer initially. Deferred gratification.