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. All vendors include some form of thermal throttling on their drives as a safeguard, 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 with a 120 mm fan directly blowing 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 degrees Celsius (measured using SMART).

Results from this test setup are not comparable to our 2019 SSD bench because we're using a different case, and a CPU cooler which generates some airflow around the CPU socket.

Reads

Writes

Please note that the sharp drops at the start of the write tests are not due to thermal throttling, but due to how the controller performs when its SLC write cache is full.

Thermal throttling happens at the 500 second mark for the uncooled drive only. Here, write rates drop to below 50 MB/s (!) for a few seconds. The reduced write rate lets the controller cool off, which restores write speeds because the drive is no longer overheating.

Thermal Image & Hot Spot

We recorded a thermal image of the running SSD as it was completing the write test. The hottest part reached 78°C, which is a very conservative point for thermal throttling. The thermal sensor reports around 10°C less than the actual temperature, which is fine, and more accurate than many other SSDs on the market.