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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Desktops > Recent iMacs with HDDs

Recent iMacs with HDDs
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Apr 6, 2017, 09:20 PM
 
Has anyone else found that iMacs bought in the last couple of years (the super skinny ones) with HDDs are just terrible?

I have customers running a bunch of them for very basic office tasks: Email, web, Office and one or two are also running Windows VMs for the sole purpose of using Sage accounting software.

They stutter, lock up and generally take forever to do anything for long periods of the day. Its a little inconsistent, sometimes they are quite snappy, but it never lasts and the more you do the slower they get. I also have some much older iMacs doing very similar jobs, 2010-2012 models Some still running Core 2 Duos I think, but all with HDDs not SSDs and these continue to run perfectly well. Since they were ok I figured even a low spec iMac that was up to 7 years newer should handle the same workload, hence some 1.4 and 1.6GHz entry level machines. I then started to wonder if those chips were up to the task but even the 2.8 with 16GB RAM is the same. This last one I even got replaced as it seemed unfit for purpose, but the replacement is identical in performance.

Its clearly not the CPU causing the problems, and 16GB RAM is plenty for running Mail, Firefox, Word and Sage, even on a Windows 10 VM. I'm forced to conclude its the 5400rpm HDDs in them. If thats right I don't know what Apple is thinking. These machines are barely usable for long periods of the day.

Anyway I'm now trying to find a way to 'fix' them. Fitting internal SSDs does not appeal. I haven't taken one apart yet but I know they are glued. Not my idea of fun.
That leaves me with an external boot drive. For some strange reason, single disk 2.5" Thunderbolt options are limited. There is a massively overpriced Lacie option, of I could get an HDD in a thunderbolt case and swap it for an SSD of my own.
Could I make do with USB 3.0?
I'd love to do some testing but I don't have any of this kit to test with and I'm not spending $300-400 on the off chance.

Any thoughts?
I have plenty of more important things to do, if only I could bring myself to do them....
     
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Apr 6, 2017, 10:48 PM
 
I haven't played with any of the glued iMacs yet, but I suspect the 5400 RPM drive. Sounds like it's intermittently bogging down under too many requests at once.

Suggest trying a 7200 RPM drive in a USB3 case. Clone the internal, and try running with it for a week or two.
     
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Apr 7, 2017, 09:34 AM
 
I guess that would be the cheapest test to run.
I have plenty of more important things to do, if only I could bring myself to do them....
     
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Apr 7, 2017, 10:57 AM
 
Note that the internal HDD in the 21.5" iMacs is a 2.5" 5400 rpm HDD. As in, the slowest drive currently on the market. I really wish Apple would just include a small Fusion Drive cache on the motherboard as standard, even something as tiny as 4GB really helps - I installed a hybrid drive with that 4GB cache for my father, and it was markedly faster.

Make sure that the USB3 case supports UAS. Not all of them do. UAS stands for USB-attached SCSI, but it is really more like Firewire over a 5Gbps interface - meaning it performs like an internal drive would. You could even put an SSD in one of them and get most of the speed back.

Another way you might test if that is the issue is by short-sleeving the drive temporarily. Shrink the boot partition to the smallest you can get away with +10% and do not make a partition on the rest of the drive. If you only use say 20% of the total capacity, this will speed up access times because the drive head does not have to move as far.

Note that the latest iMacs are not glued, per se - they use double-adhesive tape to hold the display in place. It is disassembled by cutting this tape and then replacing it with new strips after you're done. Not fun, but better than hotmelt.
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
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Apr 8, 2017, 04:10 AM
 
Across a sample of clients I have found the real world performance of the 21.5in against the most similar 27in to be orders of magnitude apart. The stupidly slow disk in the 21's is the cause I would guess. Apple's decision to cheap out on these renders the 21 really only suitable for home use in my opinion. No one expecting to do real work should be running one, unless they spring for a fusion drive setup.

Thankfully, the procedure to open it up and replace the drive with an SSD is not as hard as it looks as long as care is taken and proper tools used to cut the adhesive.

If the next iMac updates do not switch to the same on board SSD's as the laptops use then Apple has no conscience.
     
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Apr 8, 2017, 03:22 PM
 
My guess is they will with the new file system being geared more towards SSDs.
I have plenty of more important things to do, if only I could bring myself to do them....
     
   
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