The weight of a power supply primarily comes from three core components: transformers, capacitors, and heat sinks. While the materials and specifications of these parts directly affect weight, weight alone does not universally equate to quality.
Transformers
Transformers are the heart of energy conversion in power supplies, with their weight determined by the core material (silicon steel sheets) and the number of coil turns. High-end models often use high-purity silicon steel sheets and multistrand enameled copper wire, contributing to a heavier design. In contrast, budget options may employ inferior iron cores or reduce coil turns, resulting in lighter weights. For example, a 750W power supply with an active PFC + full-bridge LLC resonant topology features a 350g transformer, while a low-quality unit of the same wattage may weigh just 200g.
Capacitors
Capacitors filter and store energy, with Japanese 105℃ high-temperature capacitors (such as those from Nippon Chemi-Con or Rubycon) being bulkier and heavier than generic alternatives. Take the Power Train Cool Black Silent King 580W supply, which uses a 1000μF ultra-large filter capacitor, making it 390g heavier than the 420W model in the same series. However, some manufacturers increase weight by adding more low-quality capacitors rather than upgrading their specs, offering no real performance boost.
Heat Sinks
The material (copper, aluminum) and size of heat sinks impact weight. Copper heat sinks are denser and better at heat dissipation but come at a higher cost, while aluminum sinks are lighter and more affordable. The NZXT C1200 GOLD, for instance, uses copper-aluminum composite heat sinks weighing 450g, versus budget models with single-layer aluminum sheets that weigh under 300g.
Weight Differences Between Active and Passive PFC
Passive PFC: Relies on large inductors for power factor correction, resulting in heavier designs (e.g., a 500W passive PFC supply may weigh 1.8kg).
Active PFC: Uses integrated circuits for control, offering smaller size and lighter weight (1.2kg for the same wattage) with higher efficiency (80 Plus Gold-certified models achieve over 90% efficiency).
The Disruptive Impact of Gallium Nitride (GaN) Technology
GaN materials significantly reduce power supply size and weight. The Lenovo ThinkPlus 65W GaN "lipstick" charger, for example, weighs just 101g—40% lighter than traditional 65W adapters—while supporting 100W PD fast charging and wide voltage input. This demonstrates that technological innovation matters more than sheer component weight.
Common Weight-Manipulation Tricks
Fake PFC weights: Using iron plates or cement instead of real inductors; a $15 budget power supply was found to have a 257g iron block masquerading as a PFC inductor.
Stone-filled casings: Some overseas teardowns revealed metal boxes packed with stones, adding 30% weight with no functional purpose.
Power Output and +12V Rail Performance
A power supply’s single +12V rail output capability directly impacts CPU and GPU stability. The Phanteks AMP BH750, for instance, delivers 62.5A on its +12V rail, supporting the 600W peak power of an RTX 4090.
Efficiency and Certification
80 Plus certifications (White/ Bronze/ Gold/ Titanium) are key efficiency indicators. The NZXT C1200 GOLD, with 80 Plus Gold certification, achieves 90% full-load efficiency, compared to just 75% for some White-certified models.
Topology and Protection Features
Full-bridge LLC resonant + synchronous rectification: The 主流 topology for high-end models, offering high efficiency and low ripple.
OCP/OVP/UVP/SCP protection (Over Current/ Voltage/ Under Voltage/ Short Circuit Protection): Essential safeguards against hardware damage.
Brand Reputation and Warranty
Stick to reputable brands like Delta, Seasonic, and Super Flower for better quality control and after-sales support. The NZXT C1200 GOLD, for example, comes with a 10-year warranty, versus just 1 year for some no-name brands.
Miniaturization and Integration
Modular designs and chip-based technologies are driving power supplies toward smaller sizes and higher power density. The FSP Hydro G Pro 850W, for instance, features a 14cm compact body compatible with ATX 3.0 standards, weighing just 1.6kg.
The Limitations of Weight as a Metric
High-end models may still be heavy: The ROG Thor 1600W Titanium, with 16 Japanese capacitors and pure copper heat sinks, tips the scales at 3.2kg.
The lightweight trend is unstoppable: GaN power supplies and modular designs are challenging the old belief that "heavier is better."
A Consumer’s Action Plan
Avoid no-name products: Choose supplies with 3C and 80 Plus certifications.
Check teardown reviews: Refer to professional outlets like Tom's Hardware or Expreview for component analysis.
Test real-world performance: Use a power meter to verify output stability under load.
While power supply weight correlates with component selection to some extent, it is not an absolute indicator of quality. Innovations like active PFC, GaN technology, and modular designs are reshaping the landscape, making "heavier equals better" an outdated myth. Consumers should prioritize wattage, efficiency, topology, and brand reliability over weight alone. When selecting a power supply, focus on 80 Plus certification, single +12V rail output, and built-in protections, and validate performance through teardowns or hands-on testing.
