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Samsung 950 Pro M.2 Additional Cooling Testing

Written on June 6, 2016 by Matt Bach


In a recent article, we investigated how long it takes for a Samsung 950 Pro M.2 drive to throttle in a number of different M.2 slot locations and some of the results surprised us. In fact, in one instance we measured a 75% drop in performance after only 7 seconds!

If you are purchasing a M.2 drive because you need high transfer speeds, seeing our results probably threw up a big red flag for you. Having a high speed drive is great, but not so much if the speed only lasts a couple of seconds. Luckily, in most situations the Samsung 950 Pro drive actually lasts a good amount of time under full load before it begins to throttle. For those that need a M.2 drive to run at full speed for longer periods of time, however, we decided to run some quick tests to compare a number of different M.2 drive cooling methods.

If you prefer to skip all our testing and simply view our conclusions, feel free to jump ahead to the conclusion section.

Test Setup

While there are a number of different ways you could attempt to cool a M.2 drive, we are going to focus on the following three methods:

A basic heatsink added onto the drive. For this, we simply took a piece of 1.5mm aluminum flat stock, cut it to length, and attached it to the M.2 drive with a thermal pad and heatshrink. This is certainly not as good as using something like copper, but we had the aluminum on hand and wanted to give a simple solution like this a shot. One advantage to this method is that the M.2 drive is still thin enough to fit underneath the video card or on the underside of a motherboard.

A M.2 to PCI-E adapter with a large heatsink. This is actually what we have used in the past and while we know that it definitely helps, this will be a good chance to do in-depth testing on this cooling method.

A standard side panel fan. For this we actually tested three different levels of cooling. First, we tested a Fractal Design Silent Series R2 120mm fan at both 5V and 12V. After that, we tested a Cooljag Everflow 92mm fan at 12v. The 92mm Everflow fan is much higher flow than the Fractal fan and the smaller size actually makes the airflow a bit more targeted so more of the total CFM of airflow from the fan goes over the M.2 drive.

Our test platform is one of the ones we used in the Samsung 950 Pro Throttling Analysis article. Since we are simply comparing the different cooling methods, however, we do not need to test all the different M.2 slot locations we tested in that article.

Testing Hardware  

Asus Z170-WS

Test Hard Drive: Samsung 950 Pro 512GB M.2 x4 SSD
installed in bottom M.2 slot
CPU: Intel Core i7 6700K 4.0GHz Quad Core 8MB
CPU Cooler: Gelid Tranquillo Rev 3
RAM: 4x Crucial DDR4-2133 4GB
Chassis: Fractal Design Define R5 Titanium
(front and rear fan @ 5v)
GPU: NVIDIA GeForce GTX Titan X 12GB
OS Hard Drive: Samsung 850 Pro 512GB SATA 6Gb/s SSD
OS: Windows 10 Pro 64-bit
Software: IOMeter 1.1.0 (Performance benchmark)

Unlike our other article, we will be testing the Samsung 950 Pro in the bottom M.2 slot only as this is the only slot where adding a side fan might help (since the top slot is covered by the GPU). To see how much of an impact the ambient temperature inside the chassis has on each cooling method, we will be loading the GeForce GTX Titan X video card with Furmark to simulate the system being under a heavy load.

To make sure our results are as accurate as possible we used a combination of IOMeter .bat files and a custom AutoIt script to automatically benchmark the drive with different work loads (sequential read/write and random read/write). The script automatically wiped the drive prior to each round of testing, created the test file on the drive, then ran though each benchmark while pausing for 5 minutes between tests to ensure that the drive has fully cooled down. The total run time for each cooling method ended up being roughly three hours.

One thing you will notice in this article is that we are not showing any temperature readings from the M.2 drive. We actually logged the temperature from the drive using AIDA 64 during all our testing, but it turns out that the Samsung 950 Pro actually has two thermal sensors - one near the storage modules and one to control throttling. Unfortunately, the sensor that is read by AIDA 64 (and every other hard drive monitoring utility we tried) is actually from the thermal sensor near the storage chips, not the control sensor. The good part about this is that you can see if the drive is getting hot enough to potentially corrupt your data, but it does mean it is not a great indicator of whether your drive is close to throttling or not. We go into this in more detail in the Test Setup section of our Samsung 950 Pro Throttling Analysis article if you are interested in learning more.

Ideal (no system load) results

In an ideal situation, every component in the system is idle and producing a minimal amount of heat. In this situation, the M.2 drive should be able to run at full speed the longest before throttling due to drive temperature.

Sequential Read

Random Read

Sequential Write

Random Write

[+] View individual charts with temperature logs

Compared to the stock Samsung 950 Pro drive, all of the cooling methods gave us much, much better results. We still saw a large drop in random write performance after about 30 seconds, but since that happened in every situation regardless of how we cooled the drive we believe that this is simply always going to happen no matter what steps you take. In fact, this seems to be an indication that the drive is simply running out of overprovisioned area rather than being affected by the drive's temperature.

Overall, we were pleasantly surprised with how effective the different cooling methods were. In fact, with the system at idle the basic aluminum bar heatsink was the only cooling method that resulted in the drive throttling at all. Even in this case, the drive took about 2.5 times longer before it started to throttle and after throttling was about 10% faster than the stock drive. That is a huge improvement for what was essentially taking a piece a metal scavenged from our recycling bin and taping it to the drive.

What really surprised us was how even a small amount of airflow from a side panel fan was able to prevent the drive from throttling. The Fractal Design 120mm fan is a very quiet, fairly low flow fan when it is running at 5V and since it is six or seven inches away from the drive we did not expect it to prevent the drive from throttling nearly completely like it did.

Worst case (heavy system load) results

While the results we saw in the previous section are very interesting, they are also taken from an ideal situation where the system is not doing much work. To see how the cooling methods change when we introduce more heat into the system, we loaded the video card to 100% by using Furmark. This puts a much higher load on the video card than any normal workload, but since we are not loading the CPU at all (to ensure that the extra heat is the only thing that affects our results) it should be a pretty good simulation of a system running a heavy load (such as rendering, gaming, etc.)

Sequential Read

Random Read

Sequential Write

Random Write

[+] View individual charts with temperature logs

Unlike the ideal situation in the last section, with the GPU heavily loaded there were multiple cooling solutions that were not able to keep the drive from ever throttling. In fact, only the PCI-E adapter and the two 12V side fans were completely successful. However, even the worst performing solution (the aluminum bar heatsink) was still able to prevent the drive from throttling for three times longer than stock M.2 drive without any cooling modifications. To put this into perspective, since the Samsung 950 Pro has a read performance of 2.5GB/s, even with just the aluminum bar heatsink you would be still able to read 305GB of data (assuming you could 100% saturate the drive) before you saw any throttling.

The 120mm 5V quiet side fan was a step up from the simple aluminum bar heatsink and resulted in the drive taking 3-5 times longer to start throttling. In addition, after the drive throttled it was 50% faster than the stock M.2 drive. For such a small amount of airflow this is a pretty massive improvement, although it was not quite as good as the quiet and high flow 12V side fans which prevented the drive from throttling at all.


Compared to just a stock Samsung 950 Pro M.2 drive without any additional cooling, every single method we tested did extremely well. Even in the worst case with the simple aluminum bar heatsink, the drive took 2.5 times longer before it started to throttle compared to the stock M.2 drive with no additional cooling. If we were to rate the different methods from most to least effective, they would be:

  1. Tie between PCI-E Adapter w/ Heatsink, 120mm 12V Quiet Side Fan, 92mm 12V High Flow Side Fan. All three of these methods completely prevented the Samsung 950 Pro drive from throttling during our testing. If you fully load the drive for longer than we did (which would mean you need to read more than 875GB worth of data from a 512GB drive), the high flow side fan should perform better than the quiet side fan, but in a practical sense all three of these methods should effectively be able to prevent a Samsung 950 Pro drive from ever throttling
  2. 120mm 5V Quiet Side Fan. While this cooling method was not able to completely prevent the drive from throttling when the system was under load, it allowed the drive to take 3-5 times longer to throttle and after throttling was 50% faster than a stock Samsung 950 Pro. For such a small amount of airflow, this is a much bigger difference than we expected and means you could read 455GB of data (nearly the entire drive) or write 172GB of data continuously before you saw any drop in performance.
  3. Aluminum Bar Heatsink. Technically, this was the worst cooling method we tested but it was still a massive improvement over the stock drive without any cooling. The main downside to a simple heatsink like this is that the hotter the system gets, the less effective a heatsink can be. We only tested with a single GPU, but if you had two or more video cards under full load, it is very possible that a heatsink may be no better than a bare drive or in some situations may cause the drive to throttle even sooner.

The different methods we tested really boil down to two types of cooling: passive cooling with a heatsink and active cooling with a fan. Both can make a big difference, but one thing that was clear in our testing is that even a small amount of airflow over the drive can be extremely beneficial. While we did not specifically test it, even better would be to combine the two methods by having a heatsink on the drive along with a fan providing some airflow over the heatsink.

Keep in mind that in the real world, it is very uncommon to fully utilize a drive this fast to the same extent we did in our testing. Very few programs will actually be able to read from a Samsung 950 Pro at full speed for more than a very short period of time, but if you do have a situation where you need a M.2 drive to perform at full speed for longer periods of time this should give you an idea of what you may need to do to achieve this.

Tags: M.2, Samsung 950 Pro, Throttling