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Advice regarding Imac 27" 5K 2019 vs 2020

B

BimmerM

macrumors newbie
Original poster
Oct 3, 2020
7
0
Hi

I'm considering buying an Imac 2019 27” 5K over a 2020 model, as I don't need the extra CPU and GPU power. Other downsides are the soldered SSD in the new models, and the price.

I have an opportunity buying an Imac 27” 5K 2019 with a fusion drive (HDD and PCIe blade SSD) for a good price.

My plan is to upgrade the HDD to SSD and upgrade the PCIe blade SSD to a bigger/faster one.

A lot of youtube videos demonstrate, how to change the fusion HDD to SSD on a 2019 model, where the blackmagic speed tops around 500 mb/s afterwards, even though this Imac also has a PCIe SSD, where the OS boots from. While models that actually came with 100% SSD setup without fusion drive from the same year top a speed of 2700 - 2800 MB/s.

Can anyone explain to me, why there is so much difference between these two in speed, even with SSD setup in both, as they both use a PCIe setup ?

Do you know, if swapping both the PCIe blade SSD and the SATA in the 2019 fusion model, would achieve the same speed as the models that came with 100% SSD and no fusion drive setup, that is 2700 - 2800 MB/s, or would I need to a buy a 100% SSD model to achieve this and why ?

Thank you
 
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The SSD only version only uses the PCIe interface. The fusion uses the PCIe interface for the SSD and the SATA for the spinning drive. If you replace the spinning drive with a SSD it is limited to SATA speeds. If you want the best speeds in your scenario replace the SSD blade with one large enough for the OS, apps, and your most used files. Use the SATA SSD for infrequently used files.
 
glenthompson said:
The SSD only version only uses the PCIe interface. The fusion uses the PCIe interface for the SSD and the SATA for the spinning drive. If you replace the spinning drive with a SSD it is limited to SATA speeds. If you want the best speeds in your scenario replace the SSD blade with one large enough for the OS, apps, and your most used files. Use the SATA SSD for infrequently used files.
Click to expand...

Thank you so much for the reply.
This is exactly what I had in mind actually, but I was hoping I could reach the speed of PCIe (approx. 2700 - 2800 MB/s) with this scenario instead of only SATA speed, as I thought the OS would use the PCIe instead with a larger SSD in this spot, until all the storage is used up.

I guess this is not the case?

Is the SATA primarily used in these models to control the computer speed and the interactions overall, if it is, what is the exact purpose of the PCIe SSD then?

How can I choose to use the PCIe for the OS, apps and other files, and use the SATA SSD to other files, isn't this something the computer setup does automatically?

Any possibility to remove the fusion SATA completely, and run only PCIe just like the SSD version alone, to achieve the same speed ?

Thanks again
 
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SATA is used because that’s the only interface that works with a spinning drive. I assumed that you were planning on splitting the fusion and keeping the drives separate. You can replace both drives and rebuild the fusion drive to use both and get overall higher speed.

For the best performance you could remove the spinning drive and just replace the SSD blade with a larger size that would hold everything. Would work the same as a SSD only model.

If I was cracking the case on that model, I would replace everything I could for maximum flexibility. Not the easiest computer to open up.
 
glenthompson said:
SATA is used because that’s the only interface that works with a spinning drive. I assumed that you were planning on splitting the fusion and keeping the drives separate. You can replace both drives and rebuild the fusion drive to use both and get overall higher speed.

For the best performance you could remove the spinning drive and just replace the SSD blade with a larger size that would hold everything. Would work the same as a SSD only model.

If I was cracking the case on that model, I would replace everything I could for maximum flexibility. Not the easiest computer to open up.
Click to expand...

Thanks for explaining that.
It seems like the fusion drive is dependant of the PCIe SSD, in such a way, that it slows down the overall speed even with a SATA SSD, and it would be impossible to gain the absolute maximum performance this way.
Even if I choose to split the drives to keep them separate, or rebuild the fusion drive to use both, I would never gain the performance matching the Imac 2019 SSD only version, did I understand this correctly?

If that's the case, then I think I'll go for the second option, removing the SATA spinning drive completely to gain the best performance, and use a fast PCIe 512 - 1TB SSD instead.

What is the exact procedure to remove the spinning drive, can I just unplug the drive from the SATA connection alone, or do I need to tell the Imac not to use it, and instead only use the PCIe SSD ?

I understand, it won't be easy to open up the thing, but I believe it's worth it. What else could be a great thing to replace for maximum flexibility while I'm in there, the RAM ?
 
Coming back to my old thread here, as I haven't decided, which model to buy yet.

Can any of you guys tell me, if the iMac 2020 actually is worth it over a 2019 model?

Here I'm thinking of the reputation of reliability issues with the T2 chip, cons of the soldered SSD and GPU glitches, all on the 2020 model.
 
We've just seen what M1 can do. I think no Intel Mac is worth to buy now. Mac Intel is obsolete now with its noisy fans, thermal problems, GPU glitches and so on. It's the past.
 
cltd said:
We've just seen what M1 can do. I think no Intel Mac is worth to buy now. Mac Intel is obsolete now with its noisy fans, thermal problems, GPU glitches and so on. It's the past.
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That entirely depends on your use case(s). Mine requires that I be able to run Windows Server 2016 in VMware Fusion to test things that I do for work. So, my next will be the 2020 iMac.

I await x86 emulation on the Mx series to see how that works out. If they get emulation running that reliably can handle Windows server environments, then my next purchase after this one will probably be a Mac and not a Windows machine.
 
Jordan Klein said:
That entirely depends on your use case(s). Mine requires that I be able to run Windows Server 2016 in VMware Fusion to test things that I do for work. So, my next will be the 2020 iMac.

I await x86 emulation on the Mx series to see how that works out. If they get emulation running that reliably can handle Windows server environments, then my next purchase after this one will probably be a Mac and not a Windows machine.
Click to expand...
CrosOver might help ;)
www.macrumors.com

CrossOver Allows x86 Windows Apps to Run on Apple M1 Macs

Codeweavers posted a blog post and video tonight showing off CrossOver running on an Apple M1 MacBook Air. This video shows Team Fortress 2 running...
www.macrumors.com www.macrumors.com
 
Maybe it's better to get side Windows machine and enjoy Your Mac without such pression ;)
 
cltd said:
Maybe it's better to get side Windows machine and enjoy Your Mac without such pression ;)
Click to expand...
I'm trying to minimize how much tech I own. One thing I loved about Apple's change to Intel processors is that it flattened the tech landscape significantly. I think a lot of Mac owners became Mac owners due to this. I think a lot of Mac owners may end up leaving due to this.

Maybe someday, server environments will run on Arm. But that's currently not the case for the vast majority of them. It'll be quite a while before that happens I believe. So, holding out for decent x86 emulation.
 
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