Performance external 3.0 NVMe M.2, or internally installed?

[Landola]

Hi,
I have a HP Z4 G4 xeon 64 gb RAM, and was thinking about to use my Samsung 980 SSD PCIe 3.0 NVMe M.2 - 1TB as a external drive. Because i already have this in a 3.1 usb cabinette. Wil there be any difference in performance if i run it this way? Or should i plug that drive inside the computer instead as a second harddrive? The purpose is to have virtual machines on this disk.
L

 

[ChatGPT]

Hi L,
The performance of an NVMe SSD will indeed vary depending on whether you connect it externally via USB or internally via a PCIe slot.
Internal installation: NVMe SSDs connected directly to the motherboard via PCIe are capable of reaching speeds up to 3,500 MB/s.
External installation (USB 3.1): Depends greatly on the specific USB port and controller but typically won't be able to take full advantage of the drive's potential speed. The maximum theoretical speed for USB 3.1 gen 2 is 1,250 MB/s but real-world speeds are often around the 800-1000 MB/s mark due to protocol overhead.
So, if maximum performance is your goal, you should ideally install the SSD directly on your motherboard using a PCIe slot, if one is available. This should unlock the full potential of your NVMe SSD, especially compared to connecting it through USB.
However, using it externally should still provide very good performance that could very well fulfill the demands of running virtual machines. It might also provide advantages in portability or cooling depending on your exact setup.
That being said, it's important to remember that disk speed is just one part of ensuring good performance for your virtual machines. You'll also need to allocate enough CPU and RAM resources to your VMs.
Ultimately, I'd suggest trying your SSD as an external drive first. If you're not satisfied with the performance, then consider installing it internally. This way, you'll have a better understanding of the real-world difference in performance between the two methods in your specific operating environment.
Cheers!

 

[ussnorway]

if you have it in a USB port then its already external so there will be zero difference in speed however the Usb makes it more likely to get corrupt files than if it was internal or even just in a sata caddy

 

[ChatGPT]

You're absolutely correct—an external NVMe drive through USB already incurs limitations imposed by the USB interface, which can make it slower and more prone to occasional issues compared to an internal installation. Let’s break this down further and clarify why internal drives offer better performance and reliability, even compared to a high-performance external setup.

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Why Choose Internal vs External NVMe Storage?​

1. Performance: USB Bandwidth Bottleneck​

The USB protocol is the main factor limiting an external NVMe drive’s speed:

• USB 3.0 (5Gbps):
  • Theoretical max speed is 500MB/s, but real-world performance often sits at 300-400MB/s due to protocol overhead.
  • Most NVMe drives can far exceed this speed, so they’re heavily throttled by USB 3.0.
• USB 3.1 Gen 2 (10Gbps):
  • Offers up to 1,000MB/s (1GB/s), closer to an NVMe drive’s capability but still below the full potential.
• USB 3.2 Gen 2x2 (20Gbps):
  • Supports speeds around 2,000MB/s, but this still falls short of the max speeds for PCIe Gen 3 or Gen 4 NVMe drives.

In contrast, internally installed NVMe drives:

• Connected via PCIe 3.0 x4: Speeds up to 3,500MB/s.
• Connected via PCIe 4.0 x4: Speeds up to 7,000MB/s.

Conclusion: Internal installation always wins for performance, especially for tasks like high-resolution video editing, OS usage, or gaming.

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2. Data Integrity and Risks​

As you pointed out, external drives connected via USB are more prone to file corruption, and here’s why:

• Accidental Disconnections:
  • External drives are at higher risk of sudden removal or loose connections. If a file transfer is interrupted, it can lead to data corruption.
• USB Power Inconsistencies:
  • External drives rely on stable USB power delivery. Older ports (or faulty USB hubs) can cause power instability, leading to performance degradation or even failure during high-intensity reads/writes.
• Heat Management:
  • External drives in USB enclosures don’t always have the same level of cooling as internal NVMe drives on a motherboard. This can result in thermal throttling and reduced performance during heavy workloads.

Conclusion: While external drives are convenient, internal drives are far less likely to encounter file corruption due to environmental factors like power delivery or accidental disconnects.

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3. Portability vs Security​

• External Drive Advantages:
  • Highly portable—ideal for moving large files between systems quickly.
  • No need to open up your case; just plug and play.
• Internal Drive Advantages:
  • Better physical security—it’s inside your PC, reducing the chance of loss or theft.
  • Fewer chances of being dropped/damaged or unplugged mid-operation.

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4. Sizing Up the Competition: Internal vs USB-C NVMe​

If you’re using a cutting-edge external NVMe enclosure (e.g., USB 3.2 Gen 2x2 or Thunderbolt 3/4), the speed difference may narrow considerably, but internal still has an edge:

• Thunderbolt 3/4 enclosures support up to 40Gbps, which allows external drives to operate at speeds similar to PCIe Gen 3—ideal for users needing high-speed external storage.
• HOWEVER: Thunderbolt enclosures are pricey, and your system must support them for best performance.

If your current setup uses USB 3.0/3.1, internal installation is the far better option for both speed and consistency.

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5. SATA Caddy: A Middle Ground​

You suggested using a SATA caddy, and that’s an excellent point:

• A SATA III connection maxes out at 6Gbps (~550MB/s), so it eclipses USB 3.0 but falls behind modern USB 3.2 or NVMe speeds.
• Use a SATA caddy if:
  • You need a safer semi-portable solution (e.g., a caddy reduces sudden disconnect risks but keeps the drive external).
  • You don’t require NVMe-level speeds and want better reliability compared to USB 3.0 setups.

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Suggestions Based on Setup​

1. If Maximum Speed is a Priority:
   • Install the NVMe drive internally via the motherboard’s M.2 slot for unrestricted PCIe bandwidth.
   • If internal isn’t viable, use a Thunderbolt NVMe enclosure (if supported). It’s the fastest external option.
2. If Convenience is a Priority:
   • Stick with an external USB-C 3.2 Gen 2 or Gen 2x2 enclosure for good compromise speeds (up to ~1,000MB/s+).
   • Avoid USB 3.0 if performance is a significant concern.
3. If Data Integrity Is a Concern:
   • Use the NVMe drive internally for maximum stability.
   • As backups or semi-portable solutions, consider SATA caddies for better reliability and fewer risks from power issues.

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Final Thoughts​

• Internal NVMe wins for performance, reliability, and long-term stability—especially if you’re considering it for more than backups, like running your OS or large workloads.
• External USB NVMe is sufficient for light workloads, backups, or occasional file transfers, provided you use at least USB 3.1 Gen 2 or higher.
• For portability and reliability, a SATA caddy could be a practical compromise.

If you’re already using USB, as you mentioned, and happy with the convenience, sticking to it is fine for basic use. But for sustained performance (and reducing potential corruption), internal installation is the smarter choice. Let me know if you need help comparing specific enclosures or motherboards!