Overview
The Thermalright Peerless Assassin 120 Mini Black — Compact 135mm Dual-Tower CPU Air Cooler is a dual-tower air cooler whose height is kept to 135mm. It pairs six 6mm heat pipes (AGHP Gen4) with a 120mm TL-D12B PWM fan.
It is aimed at builders whose case cannot fit a full-size dual-tower cooler but who want more headroom than a single tower offers. The short verdict: it is a strong option for quietly cooling a Core i5 or Ryzen 5 class CPU in a compact case.
If your case has plenty of height, a taller full-size model is the more straightforward choice.
Listed dimensions are 125 x 110 x 135 mm (L x W x H). The fan tops out at 1500 RPM, and the rated noise level is 25.6 dBA.
Supported sockets are Intel LGA1851/1700/1200/115x and AMD AM5/AM4, which covers almost every current mainstream platform. As of May 2026, Amazon.co.Check the retailer's page for the latest user reviews.
That is a strong score, but the sample is still small, so treat it as a trend rather than proof.
Why 135mm Matters
Many full-size 120mm dual-tower coolers are in the 150mm-plus height range. Meanwhile, many Micro-ATX and compact mid-tower cases limit cooler height to somewhere between about 140mm and the low 150s.
That gap is why many builders drop down to a single tower. This cooler is designed to fill it.
The trade-off is fin area. A shorter stack has less surface area than the full-size version, so it has less headroom under long, heavy loads.
A simple rule works well here: buy the full-size model if it fits, and this one if it does not.
Compatibility Guide
Supported sockets:
- Intel: LGA1851 / LGA1700 / LGA1200 / LGA1150, 1151, 1155, 1156
- AMD: AM5 / AM4
The included mounting kit has hardware for each platform. The parts and steps differ by socket, so check the manual to see which pieces you need before you start.
| Check | This cooler | Where to verify |
|---|---|---|
| Case cooler height limit | 135mm | Case spec sheet, and leave a few mm of margin |
| Footprint | 125 x 110 mm | VRM heatsinks and the first expansion slot on your motherboard |
| RAM clearance | Watch out for tall modules | Your RAM height, including the heat spreader |
| Fan connection | 4-pin PWM | CPU_FAN header |
Three mistakes come up most often:
1. An exact match is not enough. If your case limit is also exactly 135mm, the side panel shape or cable routing can still stop the panel from closing.
Look for a few millimeters of spare clearance.
2. RAM interference. Dual-tower coolers tend to hang over the memory slots.
With tall heat-spreader or RGB memory, you may need to raise the fan, which pushes the total height above 135mm. The 135mm figure assumes the fan sits in its standard position.
3. LGA1700/LGA1851 mounting. Cooling performance on current Intel sockets is known to depend on mounting pressure.
Tighten the screws in a diagonal pattern, a little at a time, rather than fully tightening one side first.
The fan connects to the motherboard's CPU_FAN header through a 4-pin PWM connector, and its speed is controlled automatically based on load.
Product Info
| Item | Value |
|---|---|
| Dimensions (LxWxH) | 125 x 110 x 135 mm |
| Heat pipes | 6 (6mm) |
| Fan size | 120 mm (TL-D12B PWM) |
| Max fan speed | 1500 RPM |
| Noise level | 25.6 dBA |
| Cooling type | Air |
| Socket support | AM4 / AM5 / LGA1150 / LGA115X / LGA1200 / LGA1700 / LGA1851 |
As of May 29, 2026, the price on Amazon.co.jp was ¥7,701.
Prices change often with sales and stock levels, so check the product page for the current price before you buy. Thermalright is a Taiwan-based cooling specialist, and the Peerless Assassin line has become a standard pick for good-value air cooling.
The box includes a TL-D12B fan, the mounting kit, thermal paste, and a manual. The standard warranty is listed as two years, but coverage can vary by retailer and region, so confirm it with the manufacturer or seller.
Comparison with Alternatives
Within Thermalright's own lineup, the main differences come down to height and the number of towers.
| Model | Positioning | Best when |
|---|---|---|
| Peerless Assassin 120 Mini (this one) | Shortened dual tower | Your case limits height but you want headroom |
| Peerless Assassin 120 (PA120) | Full-size dual tower | Your case has height to spare |
| Peerless Assassin 90 SE | Dual tower with a 90mm fan | Even smaller cases |
| Assassin Spirit 120 EVO | Single-tower class | Avoiding RAM interference comes first |
Check each product page for exact dimensions and cooling figures. For high-end CPUs under sustained full load, a 360mm AIO is also worth considering.
Keep in mind that it costs more and adds a pump that can fail.
Noise and Fan Tuning
A rated 25.6 dBA is on the quiet side, but the sound you actually hear depends heavily on load and fan settings.
A 1500 RPM maximum is not a high-speed design, so the fan should not become harsh even at full speed.
Adjusting the CPU_FAN curve in the BIOS (UEFI) helps keep idle noise low while still letting the fan respond to gaming temperatures. If the fan keeps speeding up and slowing down on default settings, try a gentler response curve.
Best Use Cases
- Cases with a cooler height limit around 140mm that cannot fit a full-size dual tower
- Core i5 / Ryzen 5 class CPUs where quiet operation matters
- Builders who want to avoid AIO pump noise, leak risk, or pump lifespan concerns
- Anyone who wants more cooling than a single tower for under ¥10,000
Fitting a dual tower into 135mm gives it a good balance between ease of installation and thermal headroom.
Before You Buy
Limited headroom for high-end CPUs under sustained load. A Core i7/i9 or Ryzen 7/9 running long encodes or renders may run short on cooling at peak.
For those workloads, consider a full-size dual tower or a 240mm-or-larger AIO.
Little reason to choose it if your case has room. The whole point of this cooler is a dual tower at a low height.
If your case fits coolers in the 150mm range, a full-size model at a similar price usually offers more headroom.
Pick your RAM first. As noted above, tall memory forces the fan upward and cancels the 135mm advantage.
In height-limited cases, low-profile RAM is the safer pairing.
Check the listing details. In the Amazon listing data we referenced, the seller and shipper appeared as Amazon US even though it was an Amazon.co.jp product page.
Before you buy, confirm the actual seller, shipping source, and delivery estimate shown on the page. Also check the Mini and Black wording and the product images so you do not mistake it for the standard Peerless Assassin 120 or a different color.
**The review count is still small. That is not yet enough to judge unit-to-unit variation or early failure rates.
FAQ
Q. Can it handle a Core i7 or Ryzen 7? A.
It will mount, and for mostly gaming workloads it is often enough. Headroom gets thin under long all-core loads, so a larger cooler is recommended if that is your main use.
Q. How do I know if it fits my case? A.
Check the maximum CPU cooler height in your case specs and make sure it is at least a few millimeters above 135mm. If tall RAM means raising the fan, add that height too.
Q. Does it support LGA1851 (Core Ultra)?
A. Yes. LGA1851 is on the supported list, and the mounting hardware is in the included kit.
Q. Do I need to buy thermal paste separately? A.
No, thermal paste is included. If you remount the cooler, clean off the old paste and apply fresh paste.
Q. Is the fan loud? A.
It maxes out at 1500 RPM with a rated 25.6 dBA, which is on the quiet side.
You can quiet it further with a BIOS fan curve.
Product Disclosure (Amazon)
- Manufacturer: THERMALRIGHT(サーマルライト)
- Seller: Amazon US
- Fulfilled by: Amazon US
- ASIN: B0CQQYJC5M
- Note: This article covers a manufacturer-made product based on Amazon listing details.
