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I was trying out different external Thunderbolt 3 and USB-C enclosures for a 2TB Samsung EvoPlus NVMe SSD.

My goal is to achieve high write/read speed but in a portable package, for the workflows specific to my needs.

A common problem with all these enclosures was that all of them were heating up even when I was doing no I/O with the device. I believe laptops don’t do this, it would be a constant battery drain.

  1. Is this the result of poor controller software or the way SSDs work that requires such a waste of power?
  2. Is there a portable solution that works with a 2TB SSD and gives decent write/read performance?
Giacomo1968
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vach
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1 Answers1

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This is not a "waste of power". Power dissipation of SSD depends on traffic intensity. And the traffic intensity depends on the kind of host controller you have, and the kind of USB-to-NVMe bridge you have.

Behind the Type-C connector you will likely have a xHC (eXtensiveHostController) that supports USB 3.1 Gen2 speed (10GBps raw data rate). If you want highest performance, you will need a USB-SSD bridge that supports Gen2 USB speeds as well. More, modern USB Gen2 high-performance controllers will use UASP streaming mode (instead of old BOT - bulk-only transport), and will achieve sustained data rates of 1GBps+.

If you check power consumption of NVMe drives, you will likely see up to 3 A at 3.3V, or close to 10W of dissipated power. This power will be consumed at highest data rate for the device, which is ~1500 MBps for ordinary sticks, like shown below.

enter image description here

9-10W of power is not something to take easy without a heat sink and all-metal enclosure with thermally conductive pads.

The m.2 SATA3 drives, in contrast, can do maybe 540 MBps at most (due to SATA speed bottleneck, which is about half of USB 3.1 Gen2 data rate), so they run much cooler, and usually don't need extra cooling.

AFAIK, only few host platforms on today market can give you fast rates and hot external enclosures. These are host PCIe cards based on ASM2142/3142 chips, and Ryzen-based 2000/3000 class machines from AMD and their channel sources.

Also, heating up of external Type-C devices even in absence of I/O access is likely because the host controller has its LPM (Link Power Management) non-functional (disabled because of some issues with its functionality). Or it could be disabled in the device. So you experience can vary with each particular USB host/device pair.

Ale..chenski
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