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iMac 5k late 2015 - Time to ditch the fusion. What's best option?

O

orangefridge

macrumors newbie
Original poster
Mar 1, 2013
3
1
Getting tired of the random speed of my mac when working with audio. I run my projects from external SSD'd through the USB 3 slots but I think certain aspects of my DAW go back and fourth with the 7200 disk in the fusion and slow the whole process down making it unusable at times.


I'm thinking booting my OS off an external source might be better...maybe I'm wrong?

What's my best option moving forward to keep the machine at the fastest speed. I'm not massively savvy with this so I think my options could be this:

- Upgrade internal Flash SSD (Last resort as I don't really want it opened up_
- Somehow running an SSD from the Thunderbolt 2 port is my favoured option but I don't know best way to do this. (Can I get a TB3 caddy and just use a TB3xTB2 cable and get the max speed TB2 provides from my iMac?
- USB3 option with an SSD/Caddy or something like an external SSD drive?

Any tips welcome.

Thanks!

iMac 5k - 27inch Late 2015
4ghz i7
32gb Ram
2TB Fusion
 
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You're right about ditching the Fusion, wrong about booting from an external.

Thing is that Apple upgraded the bus in the late 2015 iMac to take full advantage of a fast 3 x4 NVMe blade.

Unfortunately, your 2015 has a tiny AHCI SSD that runs about 1/4 the speed of a fast SSD like the Samsung 970 EVO or the WD 3D Black.

It will cost about $600 to have both drives removed and a 2TB 3D Black installed — less if you do it yourself.

3D Black on amazon

There are slower NVMe 3 x4 SSDs like the
Intel 660P or the Crucial P1. They're about 2.3x the speed of the SSD you have now but they cost less. Figure about $250 for 1TB including installation and data transfer.
Crucial P1

In either case, you'll need the Sintech short adapter ($15) plus a tape kit if doing it yourself.

Lots of threads on this. If you have any doubts, have it done — $101.93 if you arrange it through Amazon; about $75 here in the Silicon Valley.
 
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Fastest, easiest, cheapest, safest way:

Get an EXTERNAL USB3 SSD, plug it in, and set it up to be the new boot drive.
Child's play on a Mac.
 
Fishrrman said:
Fastest, easiest, cheapest, safest way:

Get an EXTERNAL USB3 SSD, plug it in, and set it up to be the new boot drive.
Child's play on a Mac.
Click to expand...
12 hours — you usually don't take that long. Why you are afraid of opening an iMac, I'll never know...

The OP asked the best option and you recommended an easy one; not the best.

An USB 3 SSD operates at 2/3 the speed of the blade in there now, 1/6 the speed of a fast NVMe blade; 1/4 the speed of a slow NVMe blade. External or internal doesn't matter—the bottleneck is SATA III.

For a few hundred $, one can have the performance of a similar 2017 SSD iMac for far less money. Unless you're using apps with intense graphics, it's possible that you would notice little difference between a hot-rodded 2015 and a 2019 (if doing Photoshop or AV, don't put a dime into this — get a newer iMac or iMac Pro).
 
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mikehalloran said:
12 hours — you usually don't take that long. Why you are afraid of opening an iMac, I'll never know...

The OP asked the best option and you recommended an easy one; not the best.

An USB 3 SSD operates at 2/3 the speed of the blade in there now, 1/6 the speed of a fast NVMe blade; 1/4 the speed of a slow NVMe blade. External or internal doesn't matter—the bottleneck is SATA III.

For a few hundred $, one can have the performance of a similar 2017 SSD iMac for far less money. Unless you're using apps with intense graphics, it's possible that you would notice little difference between a hot-rodded 2015 and a 2019 (if doing Photoshop or AV, don't put a dime into this — get a newer iMac or iMac Pro).
Click to expand...
Mike do you know of a step by step video, showing the install of a NVMe blade in a late 2015 iMac.
I currently have a "Apple CTO" 256GB SATA SSD iMac and I intend to use your preferred method rather than what I have at present.ie SATA SSD
 
I have upgraded mine with a 860EVO 1Tb SATA internal SSD.
It's easy to open and cheap.
It's fast, don't listen people that think that SATA is a bottleneck in real life usage.
It's almost impossible to tell the difference with a NVME SSD without doing benchmarks.
NVME SSD are lot faster with huge sequential read/write, this is not a very common usage.
In random access, it's less visible.
You can install a NVME blade, but it's a lot more complex.
 
Off topic, I'm contemplating to get a second hand 21.5 inch late 2015 4k model with 2TB fusion, is it very slow for usage?
 
’ve spent the last month researching my options for my 5k late 2015 iMac with a fusion drive. I’ve upgraded ram to 48gb and needed more for video editing. So I went all in with an external thunderbolt 3 nvme enclosure with the Apple adapter and then hit a wall. Just wasn’t as reliable as I wanted and kind of bottle necked around 450 r/w speeds. So, then I bailed on that as there’s very little TB2 support these days. I’m now going to open this thing, leave the 1tb spinning drive, and go straight to the 24gb Apple flash. Upgrading that to a 1tb m.2 nvme with the $16 converter for proper fit. I’ll disable the fusion and crush performance with massive blade speeds. Then, I’ll have the spinner as internal backup for larger files and my 8tb seagate external for larger backups and clones. Now, if this sounds wrong to anyone, speak up please. But from my understanding, this is close to the best performance possible. Of course, upgrading the i5 to the i7 6700k 4.0ghz would probably be the only other value move to make. Anyway, thanks for all the good info in this thread!
 
Yes, it will give you the best possible performance. However, these M.2. adapters often come with their own problems, such as standby issues, crashes, etc. Don't be surprised if you find yourself opening your iMac again a few weeks or months down the road to try a different adapter. I can't tell you how common these issues and how big or small your chances of getting a lemon are but they seem flakey enough to show up on these and other forums regularly.
 
Well that’s good to know. However, i would have that same problem whether I used a 1tb by itself or a smaller 256gb fused with a sata III, correct? The potential problem arises with the blade and adapter no matter what. So essentially, the most secure, problem-free route would be to leave the 24gb in and just get a 1tb sata iii. But that’s just no fun. Also, since I’ve never opened an iMac, what’s a realistic time frame for swapping this blade out? (I’m a tinkerer at heart). Lastly, is it worth upgrading the cpu to the i7 3.4 or 4.0? Would it be an additional process to swap or is it pretty simple once I’m already in there? Worth the price for the performance gains from my i5 3.2?
 
Replacing the SATA drive is very easy. The most complex operation is to remove the screen (not difficult with the tool to cut the glue) an put it back again properly (be careful you only have one chance to stick it !).
Removing the blade is more complex. You have a lot of boards and connectors to remove, and you have more chances to brake a small connector or wire.
You also have some chances to get a bad adapter for your M2 drive.
My advice: don't stick your screen before testing for a couple of days to be sure all is OK !
You can stick it temporary with rubber band for testing.
 
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