My external NVME SSD is getting warm on a mac mini m2.
After I updated from 26.3.1 to 26.5.1 my external SSD id getting warm now, even if unmounted.
If achieves 52° C unmounted. With 26.3.1 it was about 33° only even if mounted.
Since I suspected the USB controller first I exchanged the controller and the SSD itself but it does not change anything. The new SSD with the new controller is getting warm.
Anyone else experiencing the same or has a solution?
The current version of macOS Tahoe is 26.7. Based on your post you are running an older version, so the first step is to update your Mac to the current version.
See: Update macOS on Mac - Apple Support
That aside, keep in mind that 52°C is entirely safe for an NVMe SSD. Most modern NVMe blades are rated to idle up to 50°C–60°C and will not begin thermal throttling until they hit roughly 65°C–70°C. While annoying, it will not damage your hardware.
In recent macOS updates, Apple changed how the kernel interacts with the external USB/Thunderbolt bus. In previous versions, when you unmounted a drive, macOS properly negotiated a Low Power State (LPM / U3 sleep state) with the enclosure's bridge chip (such as ASMedia or Realtek).
However, current behavior causes the OS to continuously poll or refresh the hardware bus. Even if a drive is unmounted, macOS prevents the USB controller from entering a deep sleep state, forcing the NVMe drive and the bridge chip to remain fully powered at idle. This active idle state causes NVMe controllers to run around 50°C–52°C.
How to Fix or Mitigate the Issue (if desired, not really necessary:
Turn Off Network-Induced Bus Refreshes
A major trigger for this behavior is "Dark Wakes"—where your Mac wakes its processor in the background to handle network tasks, inadvertently waking and scanning the USB bus.
Terminate Persistent USB Power via Terminal
You can use pmset to force aggressive sleep settings on your disks and prevent background network sleep cycles from keeping the controller awake:
sudo pmset -a disksleep 1 powernap 0 tcpkeepalive 0
Physically Disconnect the Drive
Because macOS currently maintains power delivery to the port even after software ejection, the only foolproof way to keep the drive at room temperature when not in use is to unplug the cable. NVMe drives lack the mechanical power-down state of spinning hard drives, meaning as long as the port supplies power, the SSD controller remains warm.
The current version of macOS Tahoe is 26.7. Based on your post you are running an older version, so the first step is to update your Mac to the current version.
See: Update macOS on Mac - Apple Support
That aside, keep in mind that 52°C is entirely safe for an NVMe SSD. Most modern NVMe blades are rated to idle up to 50°C–60°C and will not begin thermal throttling until they hit roughly 65°C–70°C. While annoying, it will not damage your hardware.
In recent macOS updates, Apple changed how the kernel interacts with the external USB/Thunderbolt bus. In previous versions, when you unmounted a drive, macOS properly negotiated a Low Power State (LPM / U3 sleep state) with the enclosure's bridge chip (such as ASMedia or Realtek).
However, current behavior causes the OS to continuously poll or refresh the hardware bus. Even if a drive is unmounted, macOS prevents the USB controller from entering a deep sleep state, forcing the NVMe drive and the bridge chip to remain fully powered at idle. This active idle state causes NVMe controllers to run around 50°C–52°C.
How to Fix or Mitigate the Issue (if desired, not really necessary:
Turn Off Network-Induced Bus Refreshes
A major trigger for this behavior is "Dark Wakes"—where your Mac wakes its processor in the background to handle network tasks, inadvertently waking and scanning the USB bus.
Terminate Persistent USB Power via Terminal
You can use pmset to force aggressive sleep settings on your disks and prevent background network sleep cycles from keeping the controller awake:
sudo pmset -a disksleep 1 powernap 0 tcpkeepalive 0
Physically Disconnect the Drive
Because macOS currently maintains power delivery to the port even after software ejection, the only foolproof way to keep the drive at room temperature when not in use is to unplug the cable. NVMe drives lack the mechanical power-down state of spinning hard drives, meaning as long as the port supplies power, the SSD controller remains warm.
Without the NVMe vendor and model, no temperature specs. Without the Mac info, no PCIe specs. Without ambient…
But 52°C isn’t out-of-spec for any NVMe devices I’m aware of, and is all of a couple of degrees warmer than a common idle-temperature range, and is excellent for an NVMe in use.
In overall general terms, anything below 70°C is usually not going to cause issues.
Which means this might be down to airflow or heatsink cooling, or ambient, or recent PCIe which gets hotter), or might just the way it is with your NVMe.
Two degrees warmer than a commonly-spec’d idle range… seems entirely sustainable.
Was just looking at specs for a new processor that in isolation draws 600 watts. That… gets toasty. Your NVMe, not so much.
Yes, i already updated to tahoe without any difference.
The problems
a) it's getting warm, that already is annoying
b) it is unmounted sometimes. With this macos behavior the temperature baseline is already 52°. Heavy usage now adds up and sometimes (not very often, maybe 1-2 times a month, the disk get unmounted automatically.
I also tested that SSD on a windows PC. The temperature is around 30° only, same as it was with an older macos.
Unfortunately the menu "Put hard disks to sleep when possible" does not seem to exist in the settings.
But I will try the terminal.
likely normal temps really
got 2 samsung usb conencted ssds connected to this windows pc right now and I would judge their temp even without being in use is about 50c too
SSDs tend to get warm or even hot to touch but 52°C is OK anyway.
sudo pmset -a disksleep 1 powernap 0 tcpkeepalive 0
didn't help.
NVME SSD is getting warm
