Replace 2019 iMac 1TB Fusion with Internal or External SSD?

[RenaldoG]

Hi everyone,

I have a 2019 5K iMac that just went out of warranty and the 1TB Fusion Drive has been very underwhelming. I bought the Samsung 870 QVO 1TB SSD and simply want to know if there will be a difference in whether I run it internally or externally. I know that there are faster options out there but it's already bought and I just wanted to know if opening up the iMac and replacing the Fusion Drive with the SSD I bought will have a significant difference compared to me using it as an external SSD boot device.

I have opened up many iMacs so I am not scared of replacing the FD with the SSD. Just want to know if there is a significant drop in performance.

Thanks for the feedback in advance.

 

[Fishrrman]

My guess is that if you get a USB3.1 gen2 enclosure like this:

MiniPro 2.5" SATA to USB 3.1 (USB-C) External Aluminum Hard Drive HDD/Solid State SSD Enclosure

The MiniPro USB-C offers the latest USB-C connectivity while providing the fastest data transfer rate available. The design features an aluminum body engineered to provide maximum protection and effective heat dissipation. The MiniPro USB-C is universally compatible with all USB & Thunderbolt 3. ...

www.amazon.com

... then you'll see speeds that are around 90% (or better) of what you would see if you mounted the drive internally.

If It was me, I'd pick the external enclosure and do it that way...

 

[mj_]

The Samsung 870 QVO is a SATA III SSD, which means its maximum performance will be 6 Gbps as that is the maximum SATA III bus speed. A USB 3.2 Gen 1 enclosure will give you at most 5 Gbps while a USB 3.2 Gen 2 enclosure is capable of up to 10 Gbps. I don't know whether or not USB 3.2 Gen 2 enclosures with internal SATA ports exist though but if they do they should perform around 20% faster than a USB 3.2 Gen 1 enclosure.

My advice is to not bother and simply connect it externally. I've been running my 2017 iMac from an externally connected Samsung 970 EVO NVMe drive in a USB 3.2 Gen 2 enclosure since August of 2020 and had absolutely zero issues since. Performance is excellent (750 MB/s read, 700 MB/s write due to FileVault2 encryption and no T2 chip), heat dissipiation is superb, and my overall experience has been flawless and very smooth.

 

[RenaldoG]

This is the speed I am getting. Write speed is obviously problematic. Any advice?

 

[mj_]

Are you getting this right from the start or does it start out at higher numbers and then drop? And which USB enclosure are you using?