Upgrade Late 2015 or buy a new iMac


macrumors newbie
Original poster
Jun 16, 2019
Hi, I would really appreciate some advice.
I've read lots of the threads on here about this but I'm still a little confused as to the answers, so please excuse any incorrect statements!

So I have a 4ghz i7 Late 2015 iMac. I'm pretty much happy with it in every way, except it has the dreaded 1tb fusion drive, that only has a 32gb SSD in. I'm a heavy Adobe After Effects and Photoshop user, and I'm starting to notice my system struggling with having multiple apps open, or large documents in photoshop.
I have 32gb of ram, which I also understand causes problems with the 32gb SSD portion of the fusion drive, when it has to save the caches to it.

I'm thinking I have a couple of options.

1. Buy the OWC kit and upgrade the internal drive, with something better.
From what I've read I think with my iMac apple just used a normal SSD, with speeds of 400mb (ish) rather than NVMe. Can I install NVMe drives into my iMac and get the 2000mb speeds, or am I stuck with an SSD?

2. Use an external SSD drive as my boot volume. I tried this with a USB 3 drive, and got the dreaded Mojave APFS long boot times. I understand I can switch this to HFS+, but worried about the long term with this, and also would the speeds be comparable to what I have now or slower?
Also, from what I understand this problem only exists on USB 3 drives, not thunderbolt. So I could get a thunderbolt 2 drive and use that and APFS? Now I understand thunderbolt 2 enclosures are almost impossible to get, so could I buy a second hand lacie thunderbolt 2, and replace this with a SSD or NVMe? I'm pretty sure the apple thunderbolt 3 to 2 adapter wont work to be able to plug a thunderbolt 3 drive into my mac.

3. Sell my current iMac on eBay and upgrade to a new iMac. I'd probably get about £1000 for my iMac on ebay, and I would probably spend £2500 on a new one. Seems a bit excessive when really all I want is a faster drive, but my iMac is 4 years old, so would probably upgrade soon anyway, but was hoping to wait and see what apple do next year, in the hope that they'd bring out a redesigned iMac. I'm struggling justifying a new iMac when most of it will be practically the same machine.

So in an ideal world I would spend a few hundred pounds to get my current iMac through until apple release a redesigned one, but would like to know what people's opinion is.



macrumors P6
Feb 20, 2009
If drive speed is the only problem, the fastest, cheapest, easiest, safest way to upgrade is to buy a USB3 SSD, plug it in, and set it up to be the boot drive.

Samsung t5 or Sandisk Extreme (or other pre-assembled drives) can do the job.
Or... get a "bare" SSD, and the enclosure (or dock or adapter) of your choice.

If you are confident of your abilities (or are willing to pay someone to do it), you could install an internal SSD and squeeze a little more speed out of it. But there's the risk of breaking something when you pry it open.
Your choice.

Whichever way you go, upgrading the drive will easily give you 2, 3, or more years of use out of it.


macrumors 68040
Jul 13, 2008
I think you're stuck with SATA on that model. I don't think you can replace the blade storage with anything but maybe a bigger one salvaged out of another Mac; I don't think Macsales sells then and if they don't odds are no one does. Whether an external NVMe SSD via Thunderbolt is faster, I don't know either, but I'd check on that. OWC did sell a Thunderbolt 2 enclosure, the Mercury Elite Dual Pro. But you'd need to use SATA drives in it. I would guess NVMe externals are pretty much only available in Tbolt 3 since that only makes sense. It is backward compatible with Tbolt 2 with an adapter, so something like this would work: https://eshop.macsales.com/shop/express-4m2


macrumors newbie
Original poster
Jun 16, 2019
Yeah, I'm not keen on the USB 3 SSD route because of the slow boot times in AFPS.

Yeah that OWC Express looks good.

I found this article:

and it seems like that's an option too, which comes out at about £400 for the Node Lite, 500gb Samsung 970 EVO, Thunderbolt Adapter, Thunderbolt lead, and PCIe adapter.

The OWC Express plus the rest would be about £510 for the same. Shame cause it seems the more elegant solution.


macrumors newbie
May 1, 2019
You just can replace the SSD with a Crucial P1 and an adapter. Works fine and costs less