A1419 IMac mid 2017 27in FUSION drive components & MEMORY upgrade

+1 to what Servant of Cats has proposed above.

Forgo the drive fusion and simply replace either component with an SSD of sufficient capacity to carry you forward. The whole point of fusion drives was to improve Mac performance within a reasonable cost by taking advantage of a small SSD component as a sort of buffer. Unfortunately, one of the disadvantages of the fusion is fragility of the software link between the two drives if either unit becomes at all flakey at.

With the cost of high capacity, fast SSD drives now being much more reasonable, you can install one with as much storage space as you might need.

As for the RAM upgrade, check your memory pressure with the Activity Monitor app. If you are consistently running in the green, then you don't have much reason to upgrade it.

Check if your Mac needs more RAM in Activity Monitor - Apple Support

As for RAM, 16 GB is a pretty decent amount.

One way to check whether you would benefit from more RAM is to watch the Memory Pressure graph in Activity Monitor while you are doing stuff that you think might need more RAM. The graph is color-coded:

• Green means that you have enough RAM for what you are doing
• Yellow means that the amount of RAM is marginal for what you are doing
• Red means that you don't have enough RAM, and this is hurting performance

AIRaquarian wrote:

I feel I have a pretty good understanding of the fusion drive and its components  What I want to know is if the fusion drive can be comprised of the PCIe SSD and a SATA SSD or doesit have to be a SATA HDD? Since the PCIe SSD should have considerably faster rates (depending on the #of channels) I would hope that it could still take advantage of the FUSION theory. ALSO,

I am tempted to increase the ram from 16 to the max but I am thinking with a 1TB PCIe SSD would I even need it? At that point wouldn't the PCIe SSD act as sort of an extension of the memory? or would it still benefit with additional ram? YOUR INSIGHTS ARE MUCH APPRECIATED. Running macOS Ventura btw

[Edited by Moderator]

It’s probably possible, but I wouldn’t bother, for two reasons:

· an SSD on a decently-fast connection is far faster than a slow HDD.

· an external SSD can be mire easily disconnected than an external.

I’d expect marginal gains fusion SSD/SSD at best, unlike the Fusion SSD/HDD gains over a slow HDD.

I’d probably put a bootable copy of macOS on the internal.

I again would discourage running Fusion internal and external. One glitch and you’re having s bad day. But here are some commands and related info:

diskutil apfs createContainer -main disk1s23 -secondary disk123s123

How to fix a split Fusion Drive - Apple Support

16 GB is decent for iMac memory. Memory for older iMac 27” models is usually not all that expensive to obtain and install, but whether you’re presently even using enough memory for the upgrade to matter?

Remember too that the computer here is a system, with a hierarchy of storage starting with processor registers and then processor cache and then main memory and then HDD or SSD and then backups somewhere. Changing the speeds in one step of the hierarchy can change the sizing needed elsewhere in the hierarchy…

Fusion exists to masks HDD performance, because bigger and faster SSDs are more expensive and HDDs are big and cheap and slow.

More memory allows larger caches and masks HDD performance.

And SSDs… SSDs have different performance than HDDs.

Since that iMac has Thunderbolt 3 ports, you could attach an external Thunderbolt 3 / PCIe NVMe SSD.

You can get those pre-assembled, or buy an enclosure and put a M.2 PCIe NVMe blade SSD of your choice into it. Either way, hooking up one of those to your iMac would be a lot easier than doing surgery on your iMac to replace the internal drive(s).

I don't know the answer to your question. I suspect it is "Yes" – but wouldn't want to give you false hope, and have you go ahead and do all the work of changing out the HDD, only to discover that the answer is "No."

I can tell you that if you replacing either component of the Fusion Drive is going to effectively destroy it – so you will need to back up the whole drive before doing anything, then replace components, then re-establish a Fusion Drive.

Not that I'd bother. I could be mistaken, but I believe that OWC sells "blade" SSDs for that iMac in sizes up to 2 TB. If you're paying a repair shop to replace the components inside that Mac (or going to all the work needed to do that work yourself), might as well put in a large blade SSD, maybe also a large SATA SSD – and keep the drives separate. You don't need the extra complication that goes along with a Fusion Drive in this era of cheap, large SSDs.

https://eshop.macsales.com/shop/ssd/owc/imac-27-inch/2013-2019

AIRaquarian wrote:

Thank you for all the input. Very helpful in keeping me grounded. I've decided to keep it simple. Putting in WD BLUE 1 TB SSD and leaving the 32gb PCIe SSD as is. Memory staying at 16. That should be a descent setup for graphics and video rendering. Besides, I am out of work so any more would probably just invoke buyer's remorse. Thanks again for your time.

If you're getting a SATA SSD, you may want to put it into a USB 3.0 enclosure and use it as an external drive. USB 3.0 isn't a whole lot slower than SATA III, and that would save you a whole lot of delicate surgery on the iMac (with the risk of breaking something) – or a $80+ labor fee (to have a repair shop install the SSD for you).

If you search on Amazon for "usb 3.0 ssd enclosure", you'll find that tool-free USB 3.0 enclosures for SATA drives are a dime a dozen. Look for one that has UASP support (most do). You should be able to find many in the $8 to $12 range. Other World Computing also has enclosures, but theirs are a bit more expensive ($25).

Hardware Overview:

 Model Name: iMac

 Model Identifier: iMac19,2

 Processor Name: Intel Core i7

 Processor Speed: 3.2 GHz

 Number of Processors: 1

 Total Number of Cores: 6

 L2 Cache (per Core): 256 KB

 L3 Cache: 12 MB

 Hyper-Threading Technology: Enabled

 Memory: 32 GB

 Boot ROM Version: 2020.80.5.0.0

 SMC Version (system): 2.47f3

Radeon Pro 555X:

 Chipset Model: Radeon Pro 555X

 Type: GPU

 Bus: PCIe

 PCIe Lane Width: x8

 VRAM (Total): 2 GB

 Vendor: AMD (0x1002)

 Device ID: 0x67ef

 Revision ID: 0x00e3

 ROM Revision: 113-C981AA-042

 VBIOS Version: 113-C9819A148P-003

 EFI Driver Version: 01.B1.042

 Metal: Supported, feature set macOS GPUFamily2 v1

 Displays:

iMac:

 Display Type: Built-In Retina LCD

 Resolution: 4096 x 2304 Retina

 Framebuffer Depth: 30-Bit Color (ARGB2101010)

Nice!

Thanks for the update.

Enjoy your "new" computer. 🙂

I just got 89 to 91 MB/s, roughly 0.72Gb/s, external SSD to \Internal fusion drive.