Alphacool
Alphacool NexXxoS ST25 Full Copper 120mm Radiator
Best slim radiator for compact custom water-cooled PC builds.
Elevate your PC's cooling with the Alphacool NexXxoS ST25 Full Copper 120mm Radiator. Engineered for optimal thermal performance, this radiator boasts an all-copper construction, including end chambers, water channels, and fins, ensuring superior heat dissipation. Its remarkably slim 25mm profile makes it ideal for Small Form Factor builds and tight spaces. The 15 FPI fin density and serrated fins work together to maximize airflow and cooling efficiency. Integrated protective plates prevent damage from over-screwed mounting hardware, offering enhanced durability for custom water-cooling loops.
$49.99
Owner Satisfaction
4.7
/ 5
Category Rank
152
/ 3597
#152 in Computer System Cooling Parts
Price vs Category Average
-67%
Below average
Material
Full Copper (End chambers, water channels, cooling fins)
/ Full Copper (End chambers, water channels, cooling fins)
Who it's for
- Enthusiasts building high-performance custom water cooling loops
- SFF builders working with tight case clearance
- Users prioritizing long-term loop stability and corrosion prevention
Who should skip it
- Overclockers pushing hardware to extreme thermal limits
- Budget-conscious builders seeking the lowest possible price
- Silent PC enthusiasts sensitive to fan noise
Performance breakdown
Airflow Optimization
Serrated fins and 15 FPI density maintain efficiency at lower fan speeds.
Build Durability
Integrated protective plates effectively guard against accidental screw damage during installation.
Installation Compatibility
Standard G 1/4 inch threads ensure seamless integration with most custom loops.
Reliability Standards
Rigorous pressure testing to 2 Bar provides peace of mind for builders.
Space Efficiency
The ultra-slim 25mm profile is a game-changer for cramped SFF builds.
Thermal Conductivity
Full copper construction ensures elite heat transfer across the entire loop.
Key Specs
Material
Full Copper (End chambers, water channels, cooling fins)
Thickness
25mm
Fan Compatibility
120mm
Fin Density (FPI)
15
Dimensions (L x W x H)
132 x 92 x 25.5 mm
Pressure Tested To
2 Bar
Thread Type
G 1/4"
Outer Housing Material
Stainless steel
Features
- All-copper construction for maximum heat transfer
- Ultra-slim 25mm thickness fits tight spaces
- Serrated fins enhance airflow and cooling
- Protective plates prevent mounting damage
- Optimized 15 FPI fin density balances cooling and airflow
- Designed for 120mm fan compatibility
- Pressure tested for reliability
What customers say
Customers highly value the Alphacool NexXxoS ST25 radiator, especially for small form factor builds needing auxiliary cooling. The core praise centers on its full copper construction, which delivers superior thermal transfer compared to alternatives. Reviewers consistently highlight the impressive performance packed into its slim 25mm thickness, making it ideal for space constrained systems. Build quality is noted as robust, featuring reliable G1/4 inch threading that simplifies installation and prevents leaks. Many users also appreciate that these radiators often require minimal pre-flushing. While inherently limited by its slim profile, the ST25 is recognized as a best in class performer for its size, offering dependable, premium cooling in a compact design.
Know before you buy
Yes, with a slim 25mm profile, this radiator is specifically designed for compact builds where space is limited. It is one of the thinnest options available, making it highly versatile for tight chassis configurations.
Yes, copper has superior thermal conductivity compared to aluminum or brass. Using copper for the end chambers, channels, and fins ensures the most efficient heat transfer possible in a custom loop.
The 15 FPI (fins per inch) density is optimized for a balanced performance, meaning it works well with both low-speed, quiet fans and higher-RPM fans. You do not need high-static pressure fans to achieve effective cooling with this radiator.
Yes, the radiator features standard G 1/4" threads, making it compatible with the vast majority of custom water-cooling fittings on the market.
The integrated protective plates prevent your mounting screws from penetrating too deeply into the radiator core. This design feature protects the water channels from accidental punctures during installation.
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