Thermalright Peerless Assassin 120 SE Review: Incredible, Affordable Air Cooling Performance

Cinebench Test Results

I first attempt to run Cinebench without power limits enforced. If the cooler can handle it, this load will use a little more than 230W. Unfortunately, I haven’t found an air cooler capable of passing this test, and Thermalright’s Peerless Assassin 120 SE is no exception.

When testing a more reasonable 200W CPU power limit, Thermalright’s Peerless Assassin 120 SE performed exceptionally well. In this workload, the CPU temperature averaged 61 degrees Celcius over ambient – the best resultI’ve seen from any air cooler I’ve tested, beating DeepCool’s AK500 by seven degrees C!

Thermalright’s Peerless Assassin 120 SE is also the only air cooler that has passed my 200W tests when limited to 50% fan speeds,  though it did get quite toasty when doing so.

200W and 140W OCCT Test Results

I usually like to run OCCT's small set stress testing for stability when overclocking, but on Alder Lake, I haven't found a cooler that's capable of handling OCCT without throttling unless power limits are enforced.

I test OCCT at 200W to demonstrate a thermally demanding load, but also with a 140W power limit enforced to show how these coolers might perform with a CPU that's easier to cool, like Intel's i5-12600K or AMD's Ryzen 5800X.

With OCCT, Thermalright’s Peerless Assassin SE continued to deliver outstanding results. While it wasn’t able to pass 200W with reduced fan speeds in this scenario, at the default fan curve it averaged 64 degrees C over ambient – once again degrees C cooler than DeepCool’s AK500!

Where things get really interesting with the Peerless Assassin 129 SE is in lower wattage loads. In fact, I had to retest these results multiple times because I couldn’t believe my own results. When limited to 140W and with fans running at the default fan curve, the Peerless Assassin SE outperformed every cooler I’ve tested – including many high-end AIOs. At 140W with fans reduced to 50% speeds, Thermalright’s cooler tied with BeQuiet’s Pure Loop 2 FX and Cougar’s Poseidon GT360 AIOs for the best cooling performance.

95W OCCT Test Results

Due to requests from our readers, I’ve begun to include 95W results, which should be broadly applicable to CPUs like AMD’s Ryzen 5 5600V or Intel’s Core i5-12400. In these lower wattage tests, the Peerless Assassin once again lives up to its name, outperforming it’s nearest rival by six degrees C when fans ran at the default fan curve, and a whopping 12 degrees C when set to 50% fan speeds.

These results are even more interesting when you consider that most coolers do worse when limited to 50% fan speeds in this test. But the Peerless Assassin does better. This is because it runs at less than 50% fan speeds in this test using the motherboard’s default fan curve.

Noise Levels and Acoustics

To test noise levels, I used the SLM25TK Sound Level Meter positioned 18 inches behind the rear of the Be Quiet Silent Base 802 PC case, and recorded early in the morning to achieve the lowest noise floor possible. The chart below shows averaged results, measured over the course of five minutes, to account for sudden sound spikes.

In all workloads tested, the Peerless Assassin 120 SE ran very quietly. When running at maximum fan speeds, it is the second-quietest cooler we’ve tested thus far. At an enforced 50% fan speed, it runs quieter than all coolers we’ve tested except for Cooler Master & Corsair’s AIOs.

Conclusion

I was truly amazed by the performance of Thermalright’s Peerless Assassin 120 SE, especially when you consider its low $36 price. I had to retest this cooler multiple times before I would believe my own testing results! It is by far the best-performing airr I’ve tested, capable of handling 200W+ with Intel’s Core i9-12900K, while running whisper silent, and it absolutely murders its competition in lower TDP workloads. Whether you care about value or not, you should consider this cooler for your next system build.