WD Black NVMe SSD (2018) 500 GB Review 25

WD Black NVMe SSD (2018) 500 GB Review

Windows 10 Startup & File Compression »

Thermal Throttling

Due to the compact form factor, M.2 drives lack the ability to cool themselves and usually have to rely on passive airflow instead. As a safeguard, all vendors include some form of thermal throttling on their drives, which limits throughput once a certain temperature is exceeded.

On this page, we will investigate whether the tested drive has such a mechanism, how high temperatures get, and what effect this has on performance. We will test the drive in a typical case and the M.2 slot between the CPU and VGA card. A second data point shows the result when a 120 mm fan is blowing directly on the tested drive. Each of the charts has time moving from left to right, with the blue line displaying transfer speed in MB/s and the red line showing the temperature in °C (measured using SMART).


In a pure read scenario, the drive doesn't throttle at all.


No throttling in writes either—very good. The drops you see across the whole chart are present in both tests—with and without a fan, so the drive's temperature can't be the reason for them. Rather, it's an effect of the relatively small SLC write cache.

Thermal Image & Hot Spot

Thermal Camera FLIR Image during Write Test

We recorded a thermal image of the running SSD as it was completing the write test. The hottest part reached 85°C, which is about 10°C higher than what the drive's own SMART temperature monitoring reports (76°C), but not critically high in any way.
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