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).
In a pure read scenario, the drive doesn't throttle at all.
Even without a fan, during writes, the drive doesn't throttle either due to temperature. The drop down to 500 MB/s you see is identical in both the cooled and uncooled test, so it's not due to temperature. Rather, it's the effect of the small 4 GB SLC write cache, as reported on the previous page.
Thermal Image & Hot Spot
We recorded a thermal image of the running SSD as it was completing the write test. The hottest part reached 90°C, which is almost 15°C higher than what's reported through SMART temperature monitoring.