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 and the M.2 slot between the CPU and VGA card. A second data point shows the result with a 120 mm fan directly blowing 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

When writing data without the included heatsink installed, we see temperatures quickly climb to 90°C, at which point the drive will start throttling, dropping speeds down to HDD levels of around 60 MB/s. A more gradual drop would be a better choice. Still, even though the chart looks bad, sustained write speed is actually quite decent with 850 MB/s, which is comparable to most other high-performance NVMe SSDs on the market.

The fan-cooled test shows two downward spikes which are present in all other write tests too, which confirms that they are not temperature related.


Once we added the included heatsink to the SSD, thermal performance is much improved, and throttling happens much later during the workload, and not nearly as often as without the heatsink.

With the heatsink installed, thermal performance is the second best of all TLC drives we ever tested, just behind the Samsung 970 EVO (the 970 Pro uses MLC).

Thermal Limits

The tests above represent a worst-case scenario for the SSD since we're running it at maximum speed for an extended period of time. Beyond that, it becomes important to look at how storage performs when it's under lighter load, which is the case with many consumer applications. For this test, we're sending a fixed-rate stream of data to the drive until temperatures have stabilized. As long as there is no thermal throttling, we'll increase the data rate and chart it below.

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.


Once we added the heatsink, temperatures were significantly reduced, reaching only 88°C.