Which iMac to keep and OS for iMac 2019

Keep the 2019 iMac.

The 27" iMac is a much nicer screen. The machine is newer and can be more productive during the remainder of its lifespan, which will likely exceed that of the 2017 model.

Upgrade the RAM by adding two more modules. You can find quality compatible RAM at macsales.com when you're ready to buy.

Upgrade the OS to macOS 15 Sequoia. That is the last OS that will run on that iMac.

This will give you the computer with the greatest lifespan of the two looking forward.

The 2017 iMac can only be upgraded to macOS 13 Ventura which is three generations behind the newest OS26 Tahoe and dropping off of Apple's support radar. In addition, MS and some other application developers have dropped support for Ventura.

Newer OS versions don't typically slow down a Mac. Other issues may, but not generally a newer OS.

And as for the browser, the problem you are experiencing now is because you're running two old and outdates versions of macOS that have olde and outdates browser versions. MacOS Mojave cannot support current browsers that are compatible with today's internet security standards. Upgrade the OS and an upgraded browser will come with it.

You will likely have to update and upgrade your old apps too, because macOS 10.15 Catalina dropped support for 32-bit apps. Any 32-bit app you have are obsolete in the modern macOS. Use this free utility to check the compatibility of your apps: St. Claire Software – Go64: https://www.stclairsoft.com/Go64/

the only POSITIVE your 2017 hardware has is its smaller/lighter footprint (and if you need to run Sierra, High Sierra)

the 2019 pros:

2019 will run Mojave through Sequoia -- 2017 stops at Ventura

27" has easily upgradeable RAM and can hold double the maximum ram of 21.5 iMac models

Both 2017 and 2019 have dual Thunderbolt 3 (USB-C) ports

The only issue with your 2019 is its Apple fusion SSD/HDD -- it's 3 percent SSD and 97 percent slow HDD

I would highly recommend having that HDD replaced with a SATA SSD (Samsung 870 EVO recommended) -- the screen assembly will need to be cut off, but only one hour labor (and you could have the dust blown out at the same time) -- WHY? -- the SATA HDD in your 2019 has around 80MBs Read/Write speeds -- a SATA SSD will have around 480 MBs (six times faster)

that swap would leave the 32gb NVMe SSD Erased -- you could pay a few more hours labor to upgrade it to a larger SSPOLARIS Apple SSD or just leave it in place as an empty 32gb drive

If you added 16 or 32 GB more RAM and replaced the SATA HDD with SSD -- the difference in user experience would be substantial

If you replaced the NVMe SSD -- and used it as your system boot volume/SSD -- the difference would also be substantial -- NVMe is five times faster than SATA SSD -- and 25 times faster than HDD (old spinning hard drives)

Keep the 2019 iMac.

In addition to the points that D.I. Johnson made,

• That 2017 iMac is an iMac (Retina 4K, 21.5-inch, 2017). Its screen has similar quality to the one on the 2019 iMac, but is smaller. (There was another "price point" 2017 iMac that had only two CPU cores and whose screen had a resolution of only 1920x1080 pixels.)
• The 2019 iMac has four user-accessible RAM slots. The 2017 iMac has only two RAM slots – and they are sealed in, requiring risky and/or expensive surgery to access them. 21.5" iMacs used to have four user-accessible RAM slots, like 27" ones, but lost that feature in 2012 when Apple made all of the iMacs really thin.
• Neither iMac has an fast startup drive. The 1 TB drive on the 2019 iMac is a Fusion Drive which combines a 7200 rpm, 3.5" desktop hard drive and a small amount of SSD storage (much less than Apple included with the original 1 TB Fusion Drives). The 1 TB drive on the 2017 iMac is a 5400 rpm 2.5" notebook hard drive, with no SSD assist to give it any boost at all. Either iMac might benefit from using an external SSD as a startup drive.

I have a 2019 27" imac. I would recommend you just use that model as already suggested. I would not recommend trying to open the unit up to replace the drive. If you find it is not running fast enough then use an external Thunderbolt drive to boot from. I have that setup and works great for Intel Macs. You can use an app like Carbon Copy Cloner to make your bootable drive.

With respect to the Mac that you decide to get rid of: Be sure to back up / save / transfer any data that is important to you. Then see this article:

What to do before you sell, give away, trade in, or recycle your Mac - Apple Support

consider a THUNDERBOLT 3 enclosure -- for read/write speed

those numbers are the same on both 2017 and 2019 hardware

I RECOMMEND specifically (pictured):

ACASIS TBU405 Pro 40Gbps M.2 NVMe SSD Enclosure, with Cooling Fan, TBU 405 Pro for M1 M2 Pro/Max, Compatible with USB4/USB3.2/3.1/3.0/2.0, M.2 Enclosure Support 2280/2260/2242/2230

For Data SSD:

WD_BLACK SN850X NVMe Internal Gaming SSD Solid State Drive - Gen4 PCIe, M.2 2280

For boot SSD I would go with a premium SSD like:

SAMSUNG 990 PRO SSD NVMe M.2 PCIe Gen4, M.2 2280

Make sure it has the latest firmware: 5B2QJXD7 (macOS can't flash it - i just sent two of these cards back to Samsung for flashing

older Samsung NVMe SSDs seem to throttle down write speed to 900MBs when used externally so I use them accordingly

the ACASIS enclosure easily swaps M.2 SSDs - a second enclosure will provide a lot of versitility since case #1 will be the boot -- for example, the 2nd enclosure could handle data storage, and swap SSDs to manage TimeMachine and clone systems -- all at blazing speeds

ashima_108 wrote:

You mean an external SSD drive as described in this video: https://youtu.be/cfEv4MZzWLM? This may just take care of it instead of adding RAM?

I didn't watch the video – but yes, it frequently turns out that a slow drive is more often a cause of performance problems than a lack of RAM. [EDIT: Although you may want more than 8 GB if you are going to be running Sonoma or Sequoia.]

A slow drive will cause the Mac to be

• Slow to start up
• Slow to launch applications

and will also make performance worse if your Mac doesn't have enough RAM, and is going to the startup disk too often in an attempt to slowly simulate more.

If I was to get the Sandisk one, would I need 2TB ($180 on Amazon) or would 1TB ($140 on Amazon) be enough? It seems for $40 difference, if I am unsure...it is worth getting the 2TB?

SanDisk would not be my personal preference for an external SSD after seeing some of the articles on PetaPixel, ArsTechnica, and Tom's Hardware about alleged SanDisk SSD failures. Hopefully SanDisk fixed the problems – but reading those articles left me a bit nervous.

You're welcome.

Back at ya!

ashima_108 wrote:

It appears more memory can be added to the 2019 iMAC (currently, it has 8GB installed combined (4GB+4GB) but there are still two empty slots.) I assume it would be better to add memory to the 2019 iMAC and it should still run well for a few years? I guess the question is if it is worth buying the memory for the two slots and what memory should I buy?

Macs can be picky about RAM, so I would suggest buying RAM only from Other World Computing.

Other World Computing – OWC Memory Upgrades For 27" iMac with Retina 5K Display (2019 - 2020)

Crucial used to be another "go to" vendor for RAM that was guaranteed to be compatible with Macs, but they got out of that business.

I mainly will need it for browsing and hopefully having a few big googlesheets open at the same time without worrying it will freeze. I got the iMAC 2019 from a friend who said that it was slow but she was using it to edit videos, which I am not planning on doing in general.

Unless there are hardware failures, "slow" is likely to be due either to the slow 1 TB Fusion Drive, or to there being software installed on the Mac that is bogging it down. There are situations in which more than 8 GB of RAM would be desirable, but it may be that an external SSD would buy you more than more RAM. (Especially given that RAM upgrade kits seem to be going up in price.)

Question 2

Assuming the winner is the iMAC 2019, what version OS should I update to? Sometimes updating to the latest is not necessarily the best OS for the iMAC because it may slow it down? I tried opening a googlesheet and it just would not work saying "This browser version is no longer supported. Please upgrade to a supported browser."

The latest version of Safari requires Sonoma or later. You'd need to be running either Sonoma or Sequoia on the 2019 iMac to receive it. (The only Intel-based iMac that can run Tahoe is the 27" 2020 one.)

The current version of Firefox will run on Catalina or later, and the current versions of most other major third-party browsers require Monterey or later. Google says that Chrome, Firefox, Safari, and Microsoft Edge are the browsers that they support for Google Workspace.

Google Support – Supported browsers for Google Workspace

ashima_108 wrote:

You mean an external SSD drive as described in this video: https://youtu.be/cfEv4MZzWLM? This may just take care of it instead of adding RAM?

There is a way that you may be able to tell if you need more RAM.

Run Activity Monitor (Applications > Utilities > Activity Monitor), with the Memory tab selected, while doing stuff that would put a load on RAM. Then look at the Memory Pressure graph and the "Swap Used" number next to it.

• The Memory Pressure graph is color-coded. Green means that macOS believes that you have sufficient RAM. Yellow means that RAM is marginal. Red means that a lack of RAM is hurting system performance.
• Swap Used tells you the extent to which the system has been forced to go to the startup drive (on your iMac, that 1 TB Fusion Drive) to slowly simulate RAM that it doesn't have.