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, in 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).

Reads

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

Writes

Without a fan, the drive doesn't throttle for a long time, only after several minutes we start seeing the first signs of very slight throttling that really doesn't affect throughput a lot. Very impressive, especially considering that the 970 EVO doesn't come with a heatsink.

Thermal Image & Hot Spot

We recorded a thermal image of the running SSD as it was completing the write test. The hottest part reached 110°C, which is significantly higher than what the drive's own SMART temperature monitoring reports.