The King of top down cooling: Thermalright SI-100 SFF Cooler Review

Recently I tested DeepCool’s entry into top down cooling with the AN600. Today’s review we’ll be taking a look at Thermalright’s SI-100, another top down cooler for SFF builds. This unit features six staggered copper heatpipes and a thicker heatsink than its competitors paired with a full size 120mm fan, which allows it to outperform all of its competitors and claim the title of the king of top down cooling.


  • Strongest overall performance of it’s class
  • Best noise normalized performance of its class
  • Reasonable price


  • Loudest maximum noise level for coolers of this class
  • Taller than most coolers of this class

The SI-100 features a top down cooling design which not only cools the CPU, but the downward airflow can help cool your motherboard’s VRMs, RAM, and even NVMe SSD to an extent.

  • 6 Staggered Heatpipes, Thick Heatsink

The SI-100 arrives with a heatsink thicker than most of its competitors, with six staggered copper heatpipes – two more than the usual four included with other coolers of this type. These design choices give the SI-100 a performance boost which allows it to outperform it’s competition to be the king of top down cooling.

  • Full Size 120mm fan, but extra fan clips for 15mm fans are included

The SI-100 arrives with a full size 2000 RPM 120mm TL-E12 model fan which, as our benchmarks will show, performs very well. However, Thermalright recognizes that some users will prefer to have a lower clearance – as such, they have included fan clips for 15mm fans for use with this cooler.

  • Tube of Thermalright TF7 Thermal Paste

While many competitors only include pre-applied thermal paste or only a small tube sufficient for one or two installations, Thermalright includes a medium sized tube which enough paste for a few installations.

While the MSRP of this unit is officially $29.99 USD, it can be frequently found for less. As of this writing, it’s available for only $24 USD on

Packing and Installation

The heatsink of the SI-100 is protected by plastic covering, a cardboard top, and molded foam.


Included in the box are

  • Heatsink
  • 120mm fan
  • Tube of TF7 Thermal Paste
  • Fan clips for standard and slim 15mm fans
  • Mounting for Intel and AMD Platforms


AM5 and AM4 users will start installation by removing the default retention tabs.

Next you’ll place the red standoffs on the mounting holes. Take each mounting bar and secure it on top of the standoffs using the included thumb screws.

After applying thermal paste to the CPU, take the heatsink and press it against the mounting bars. Use a screwdriver to secure the heatsink to the mounting bars.

The last step is to secure the fan against the heatsink using the included fan clips, and then attach it to your motherboard’s PWM header.

Test Platform Configuration and Testing Methodology

CPU Ryzen 7700X
Motherboard Gigabyte A620I AX
Computer Case Silverstone SUGO 14

There are a lot of choices to choose from for SFF cases, ultimately I settled on Silverstone’s SUGO 14 because I liked the ability to use a 5.25″ bay or a 240mm AIO if desired. I’ve left it in the default configuration – that is, only using the single rear exhaust fan included with the case. I feel like most users of SFF cases won’t be using the hottest CPUs like Intel’s i9-14900K or AMD’s Ryzen 9 7950X, and I’ve opted to use AMD’s Ryzen 7 7700X instead. Outside of the noise normalized results, noise levels are measured while tied to the default fan curve of my motherboard to represent an “out of the box” experience.

While in most reviews I included comparison results from coolers of all types, for this review I’ve limited the comparison coolers included to only those of the SI-100’s class. Top down coolers are unique, and you can’t really compare the performance of them to something like a 240mm AIO.

Observant readers may notice that the noise graphs start at 35 instead of zero. This is because my sound meter cannot measure sound levels lower than 35 dBA. This makes it the “zero” for testing purposes. For those concerned that this might distort results – there’s no worry. If anything, the graphs above will minimize the differences in noise levels because dBA measurements are logarithmic. For a  detailed explanation of how decibel measurements correspond to perceived noise levels, please check out the video below from BeQuiet! which makes it easy to visualize and understand the true impact of of increasing dBA levels.

Ryzen 7 7700X Cooling and Acoustic Results

Maximum Cooling Power

Most coolers reach TJ Max, the maximum temperature of the Ryzen CPU of 95 degrees Celsius, under a maximum intensity load. Because of this, for a maximum intensity workload we’re measuring the CPU package power rather than the CPU’s temperature.

Thermalright’s SI-100 cooled 113W during the course of testing, taking the title of king of top down cooling by allowing the CPU to handle 9W more than it’s nearest competitor from DeepCool can handle.

Maximum Noise Levels

Performance is only one part of the picture, noise levels are equally important. With noise measured at 44.9 dBA, Thermalright’s SI-100 is the loudest top down cooler I’ve tested thus far.

If you’re particular about noise levels, the next benchmark review results will show you how it performs when it runs quietly.

Noise Normalized Performance

For noise normalized testing, I’ve set the fans to a low 37.3 dBA. This is a very low, but slightly audible noise level, and shouldn’t bother anyone.

With the unit’s fan set to this low noise level, the SI-100 cooled 106W on average during the course of testing. That’s an impressive 8W more than it’s closest competitor.

95W Results

While maximum performance is important, most of the time you won’t be pushing the CPU to its limits. It’s good to see how a cooler performs in more typical situations. A 95W workload is higher than most users will see in common tasks, and might represent the most CPU intensive of games.

With a CPU temperature of 58C over ambient, Thermalright’s SI-100 outperforms its nearest competition from Scythe and DeepCool by 8C, and outperforms Noctua’s and BeQuiet’s solutions by an impressive 11C!

75W Results

75W is the lowest level of power I test, and it’s similar to what users will consume with this CPU in most games. The result of 43c over a 23c ambient is very impressive for a top down cooler of this type, outperforming the nearest performing competitors from Scythe and Noctua by 6C.

While these thermal results are interesting, noise levels are generally more important here. Thermalright’s SI-100 registered at 42.9 dBA when tied to the default fan curve of my motherboard. This is tied with DeepCool’s AN600 for the second loudest result I have here, and while normally I might consider this louder performance bad it’s paired with chart topping thermal performance – and if you really want to run this cooler silently, my previous noise normalized results show that it will do well even when tuned to low noise levels.


Thermalright’s SI-100 is the king of top down cooling,  the strongest I’ve tested capable of fitting a SFF case that I’ve tested. However, it is taller than most of it’s competitors and that may cause compatibility issues in the slimmest of cases. The fan on this unit can run loudly by default, but that’s not a concern because even when tuned for low noise levels the SI-100 outperforms all of its competitors. If I was going to build a SFF system with a top down cooler, I’d be using Thermalright’s SI-100.

The strongest top down SFF cooling on the market

  • Strongest top down cooler on the market
  • Chart topping noise normalized performance
  • Runs loudly by default
  • Taller than its competition

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