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

KLEVV declares the included heatsink as "optional," so I can our first test without the heatsink, without any additional airflow. As you can see, the drive throttles fairly quickly. On the other hand, if you have only light workloads, that last for just a few seconds, then throttling won't be an issue.

Drive with Included Heatsink

Next up, the included heatsink. It does pretty well, but will throttle eventually. Still, the time before throttle is improved quite a bit. If you have the physical space in your case, do install the heatsink, it takes just a few seconds.

Drive with Thermalright Heatsink

I also installed a Thermalright TR-M2, which is a compact full-metal heatsink. Still quite some throttling, but better.

Drive with big Thermalright Heatsink

Even with a much bigger Thermalright HR-10, there's a little bit of thermal throttling.

Drive with Fan

Finally, to find out what's possible, and as control, I put a big 80 mm fan in front of the drive with the stock heatsink, to achieve as low as possible temperatures. Quite surprising—there is still a little bit of thermal throttling.

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 71°C.