Comparing different iMacs generations

[Fliu]

I'm looking to purchase a secondhand iMac and comparing multiple iMac across different generations.
Which would you purchase?

2014 iMac 27" 5K not P3 1TB Fusion (128 SSD + 1TB HDD) 16 GB RAM (upgradable) CPU Single: 916 Multi: 2926 Radeon R9 M290X Metal: 23625

2015 iMac 21.5" 4K P3 256 SSD 8 GB RAM (not upgradable) CPU Single: 891 Multi: 3033 Intel Iris Pro Graphics 6200 Metal: 6267

2017 iMac 21.5" 4K P3 1TB HDD (boot w/TB3 SSD) 8 GB RAM (not upgradable) CPU (hardware HEVC decoding) Single: 872 Multi: 3032 Radeon Pro 555 Metal: 12266

CPU performance seems pretty similar across all three but the 2017 has hardware-accelerated HEVC decoding.

Does the GPU performance of the 2014 make that big of a difference?

Would an external USB3/TB2 improve read/write speeds over the 2014 Fusion drive?

 

[Juicy Box]

What do you plan on doing with it?
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Just based off of the info given, I would go with the 2014. Better Fusion Drive, more RAM, upgradable RAM, better GPU.

But, I guess other information, such as budget, price, and intent would matter.

 

[Juicy Box]

Would a external USB3/TB2 improve read/write speeds over the 2014 Fusion drive?

It depends on what you would do with it.

I use a 1TB Fusion Drive on my Late 2012 iMac, and the if using the SSD part of the Fusion Drive, the R/W speeds are faster than external USB 3.0 and TB1 drives.

But, if using the HDD part, they drop a lot.

If you do very repetitive tasks using your Fusion Drive, you may always see the faster speeds. Also, the Fusion drives set aside a few GBs of space free to use for new tasks, so if you are not dealing with large file sizes, you might be okay.

I wouldn't recommend the 1TB Fusion Drive on the Late 2015 iMac and up, due to the tiny SSD portion.

 

[padams35]

If the price is equal it looks like a toss up between the 2014 and 2017. Anything a 2015 can do a 2017 with an external SSD can do a little better.

So ask yourself what is more important: lots of RAM (2014) or the newer ports (2017)?

 

[Fishrrman]

Get the 2017 (preferably from the Apple-refurbished online store).

It has USB-c and thunderbolt3 -- BIG jump ahead speed-wise.
Plus it has 4 USB-a ports as well.

If you can, get either a 512gb or even 256gb internal SSD.
That will keep it running "faster for longer".
Add USB3 external storage if you need "more room".

 

[Fliu]

Just based off of the info given, I would go with the 2014. Better Fusion Drive, more RAM, upgradable RAM, better GPU.

If the price is equal it looks like a toss up between the 2014 and 2017. Anything a 2015 can do a 2017 with an external SSD can do a little better.

So ask yourself what is more important: lots of RAM (2014) or the newer ports (2017)?

My concerns with the 2014 are that the 2GB GPU would struggle.

Per Appleinsider: "Many people complained about stuttery user interface with the previous base graphics, and that was likely because of the measly 2GB of video RAM, which is taken up by the roughly 15 million pixels of the 5K display leaving almost nothing for programs to use."

Anyone notice this with the 5K before they moved to desktop GPUs?

 

[Juicy Box]

Anyone notice this with the 5K before they moved to desktop GPUs?

Maybe someone else has experience with this, as I haven't used any Mac newer than my Late 2012 iMac.

I remember on Blizzard's Mac support forum 5K iMac users were complaining about WoW not actually displaying 5K. IIRC, it was blamed on the GPU, that it was not capable of running WoW 5K.

Although, I think an argument was that there wasn't any GPUs capable of running WoW in 5K at the time, but I am not positive about that last part.

I don't play WoW anymore, but I do play WoW Classic, and my Late 2012 27" iMac with the 2GB NVIDIA GeForce GTX 680MX is able to play WoW Classic at full settings. This isn't on 5K of course, but still, that GPU is a beast.

 

[padams35]

My concerns with the 2014 are that the 2GB GPU would struggle.

Per Appleinsider: "Many people complained about stuttery user interface with the previous base graphics, and that was likely because of the measly 2GB of video RAM, which is taken up by the roughly 15 million pixels of the 5K display leaving almost nothing for programs to use."

Anyone notice this with the 5K before they moved to desktop GPUs?

15 million pixels at 10b/color x3 colors is 60MB. Realistically you need 5-10x more than that, but that will still be well under a GB of Vram used for basic email/internet/office work. (Gaming in native 5K with just 2GB Vram however is usually futile).

The 2015 base level M380 which received the complaints was just slow by 5K standards.

The only 5K I've used was the 2015 M395-2GB, and that one had zero stutter.

 

[retta283]

The question I have is will the difference in display size be an issue? What size are you using now? I'm using a 21.5, but next time I buy I will most likely go 27", I like big displays. Not to say the 21.5 is bad, but it may be too small if you're used to something larger.

Do be careful of the 2014 5K for the reasons stated above, you may be able to get a deal on a 2015-17 27".

If you only pick from the three presented options, I'd go for the 2017.