Thermal Throttling

Due to the compact form factor, M.2 drives lack the ability to actively cool themselves, usually having 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, installed 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 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 older SSD benches because we're using a different case and an AIO watercooling unit, so there's very little airflow inside the case.

Bare Drive without Heatsink

There are various levels of throttling, in both read and write, but for light loads that don't last for very long there is no throttling. Also, the throttling is very well-behaved, changing rates in small steps, without falling off a cliff.

Drive with Thermalright Heatsink

I also installed a Thermalright TR-M2, which is a compact full-metal heatsink. Now there is no more throttling, very good.

Drive with Fan

Finally, as control, I put a big 80 mm fan in front of the drive without heatsink, no throttling here, either.

Thermal Image & Hot Spot

We recorded a thermal image of the running SSD as it was completing the write test. The surface temperature of the drive reached 97°C, which is close enough to the software sensor readings (note the green temperature line, not the red one).