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, in the M.2 slot between the CPU and VGA card, while it's getting hammered by non-stop incoming writes. A first test run, to create a baseline, shows temperature and performance with a 120 mm fan directly blowing on the tested drive. In a second run we'll report thermal performance of the completely uncooled 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

Despite the heatspreader foil, the Rocket 4 Plus throttles relatively quickly, and the throttling is very aggressive since the drive pretty much stops for a few moments.


Installing the big aftermarket heatsink completely eliminated the throttling.

Thermal Image & Hot Spot

We recorded a thermal image of the running SSD as it was completing the write test. The hottest part on the drive reached 78°C, which is close enough to the software reported temperature of 73°C.