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Highest possible transfer speeds when using an external ssd nvme m.2

Hello, I am about to migrate from a desktop Windows PC to a Mac Studio (2023 M2 Max 12-core/32GB/30-Core GPU/512GB SSD).


The issue is that I also want to use my hard drive, a Kingston KC3000 SSD 2TB M.2 NVMe PCI Express 4.0 that features R/W speeds of 7000mb/s. I obviously need to put it inside an external case. How can I utilize the full potential of such high speeds?


What type of internal connection should the case have to communicate with the drive and what type of connection is required for such high speeds? My guess is that the enclosure should have PCI-E 4.0 for the internal connection and at least USB 3.2 Gen 2x2 for the connection port (probably in USB-C form).


Another question is about use cases for the Mac Studio. I will mostly use it for photo editing (Photoshop etc.) and creating video tutorials via a screen capture app and processing the videos with an app. I use a Eizo CS2731 2K monitor. Does screen resolution relate to write speeds? If I switch to a 4K monitor in the future will I need faster write speeds compared to a 2K screen capture?


thanks in advance

Theodore

Mac Studio (2023)

Posted on May 4, 2024 10:08 AM

Reply
2 replies

May 4, 2024 2:50 PM in response to Sol_Invictus

Sol_Invictus wrote:

The issue is that I also want to use my hard drive, a Kingston KC3000 SSD 2TB M.2 NVMe PCI Express 4.0 that features R/W speeds of 7000mb/s.


That's a SSD. A hard drive would be a mechanical drive with rotating platters, and heads that had to be moved into place over them. It wouldn't be capable of speeds nearly that fast!


What type of internal connection should the case have to communicate with the drive and what type of connection is required for such high speeds? My guess is that the enclosure should have PCI-E 4.0 for the internal connection and at least USB 3.2 Gen 2x2 for the connection port (probably in USB-C form).


Mac Studios implement

  • Thunderbolt 4 ("up to 40 Gbps") (backwards-compatible with Thunderbolt 3, which is also "up to 40 Gbps")
  • USB4 40 Gbps
  • USB4 20 Gbps (inferred, because the USB4 standard mandates it)
  • USB 3.1 Gen 2 ("up to 10 Gbps")


They do not implement USB 3.2 Gen 2x2. If you put something into a USB 3.2 Gen 2x2 case and connect it to a Mac, the link will fall back to USB 3.1 Gen 2 speeds ("up to 10 Gbps").


That SSD's top speed is 7000 MBps – or 56 Gbps. So if you're actually doing a lot of large transfers where that speed matters, what you want is a Thunderbolt 3, Thunderbolt 4, or USB4 40 Gbps enclosure. USB4 data transfer modes, based on Thunderbolt 3 technology, are relative newcomers, so I believe that you will mostly be looking at Thunderbolt 3 and 4 enclosures. (I do know of one USB4 40 Gbps enclosure – from OWC. They claim that when attached to a USB4 40 Gbps port, it offers "Up to 3151MB/s real-world performance..")


Another question is about use cases for the Mac Studio. I will mostly use it for photo editing (Photoshop etc.) and creating video tutorials via a screen capture app and processing the videos with an app. I use a Eizo CS2731 2K monitor. Does screen resolution relate to write speeds? If I switch to a 4K monitor in the future will I need faster write speeds compared to a 2K screen capture?


Yes, and no. A UHD screen has a bit over 8 million pixels, and so, assuming 8 bits per channel, an uncompressed screen image could take up roughly 24 megabytes. In practice, you will likely be capturing images in JPEG format, which uses lossy compression. I took a JPEG snapshot of my screen. Photos reports that it takes 2.4 megabytes.


Even a mechanical hard drive might be able to do sequential writes at 100 megabytes per second. Meaning that writing one JPEG screen image would take something like 1/40th of a second once all the data was ready and the mechanical heads were in the right place.


So no, you won't need something faster than the Mac Studio's internal SSD, or than this Kingston SSD, just to deal with screen capture snapshots from a 4K monitor.

May 4, 2024 10:45 AM in response to Sol_Invictus

Maximum speed attainable will be limited by the speed of the ThunderBolt bus when used in a genuine ThunderBolt enclosure. USB enclosures have fewer data conductors, so speed will be slower.


Intel ThunderBolt-3 Macs can get up to nominal 2500 M Bytes/sec on an appropriately fast SSD drive in a ThunderBolt-3 enclosure, provided they use a non-busy ThunderBolt controller on the Mac (not shared controller busy servicing displays or other drives on a second Mac port) supported by a typical 32 G bits/sec (PCIe2 x4, or PCIe3 x2 amount of bandwidth).


Apple M-series Macs have one ThunderBolt controller per port, so completion is not much of an issue.


Cable lengths of over one meter are not recommended.

Highest possible transfer speeds when using an external ssd nvme m.2

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