NZXT C850 Gold Core - 850W ATX 3.1 Power Supply - 80 PLUS Gold - Cybenetics Plat vs JUSTOP Black 700W Power Supply Unit ATX PSU With 120MM Quiet Fan

Power Capacity and Certification

The NZXT C850 Gold Core provides a higher power output of 850W compared to the JUSTOP Black’s 700W capacity. This difference makes the NZXT model better suited for more demanding systems or future upgrades requiring extra power headroom. The NZXT C850 is ATX 3.1 certified and supports PCIe 5.1, indicating compatibility with the latest generation of GPUs, whereas the JUSTOP Black adheres to Intel ATX 12V v2.3 and EPS 12V v2.92 standards, which are slightly older but still broadly compatible.

This means if you aim for a build with cutting-edge components or plan to use next-gen NVIDIA graphics cards, the NZXT C850 Gold Core’s higher wattage and newer certification provide a more future-proof foundation. The JUSTOP Black’s 700W output remains sufficient for mid-range or budget builds but lacks the modern interface support that the NZXT offers.

Efficiency and Energy Consumption

When it comes to efficiency, the NZXT C850 Gold Core significantly outperforms the JUSTOP Black. It boasts an 80 PLUS Gold certification and Cybenetics Platinum efficiency rating, which ensures reduced power consumption and heat generation under load. In contrast, the JUSTOP Black has around 70% efficiency, which is notably lower and can lead to higher electricity costs and increased heat output.

The NZXT’s higher efficiency means it delivers more stable power with less energy loss, making it a more environmentally and economically sensible choice, especially for users running their systems for long periods. The JUSTOP Black’s efficiency level may be adequate for occasional or basic use, but it does not match the energy-saving advantages of the NZXT.

Noise and Cooling Performance

The NZXT C850 Gold Core is designed for whisper-quiet operation, certified by Cybenetics with noise levels below 15 dBA for this model. It features a 135 mm fluid dynamic bearing fan with Zero RPM mode, which turns off the fan during light workloads for silent operation. This makes it ideal for users prioritising a quiet PC environment.

On the other hand, the JUSTOP Black comes equipped with a 120 mm quiet cooling fan but has a noise level of around 40 dBA, which is substantially louder. While still relatively quiet for a budget PSU, it is unlikely to match the near-silent performance of the NZXT. For those sensitive to noise or who prefer a low-noise workstation or gaming setup, the NZXT’s advanced fan technology and quieter operation are clear advantages.

Compatibility and Connector Options

Both power supplies support standard ATX connections, but the NZXT C850 Gold Core offers more comprehensive compatibility, especially for modern GPUs. It supports AMD and NVIDIA graphics cards with a dual-colour 12V-2x6 connector and up to three 8-pin PCIe cables, which is beneficial for high-end GPU setups. The JUSTOP Black provides a single 8-pin (4+4) 12V rail and one PCIe 8-pin connector, sufficient for most mid-range builds but potentially limiting for multi-GPU or power-hungry cards.

In terms of connectors, the JUSTOP Black features a wide range including six SATA connectors, three Molex 4-pin, and one floppy drive connector, which could be advantageous for older or mixed hardware builds. The NZXT’s detailed connector count isn’t specified, but its focus on next-gen GPU support suggests a more modern connector set tailored to current hardware trends.

Protection and Safety Features

The JUSTOP Black explicitly lists multiple protection mechanisms, including over voltage, over power, short circuit, and thermal overload cut-off protections, and holds certifications such as CE, FCC, UL, and TUV Electrical Safety. These protections enhance system safety and reliability, particularly for users concerned about electrical faults.

While the NZXT C850 Gold Core does not detail specific protection features in the provided data, its Cybenetics Platinum efficiency and noise certifications imply a high standard of build quality and safe operation. However, the JUSTOP Black’s transparent listing of multiple specific protections and safety approvals may reassure buyers prioritising explicit safety credentials.

Build Quality and Design Features

The NZXT C850 Gold Core emphasises a high-quality build with a 135 mm fluid dynamic bearing fan designed for longevity and quiet operation, and zero RPM mode for silent low-load performance. Its ATX 3.1 certification and PCIE 5.1 readiness highlight a design focused on modern hardware compatibility and efficient power delivery.

The JUSTOP Black, while more budget-oriented, offers a robust 120 mm cooling fan and a power supply form factor compatible with standard ATX builds. It also includes a variety of connectors to accommodate older hardware peripherals, which may appeal to system builders working with legacy components. However, its lower efficiency and higher noise levels suggest a less refined design compared to the NZXT.

Price and Value for Money

The JUSTOP Black 700W power supply is priced at £29.95, making it a highly affordable option for budget-conscious buyers or those building entry-level systems. In contrast, the NZXT C850 Gold Core costs £89.99, reflecting its higher wattage, superior efficiency, quieter operation, and modern compatibility features.

While the NZXT demands a premium price, it delivers value in the form of future-proofing, energy savings, and quieter running. The JUSTOP Black offers good value for straightforward builds where budget constraints outweigh the need for cutting-edge features. Ultimately, the choice depends on whether the higher cost aligns with the need for performance and efficiency improvements.

Which should you buy?

Choosing between the NZXT C850 Gold Core and the JUSTOP Black 700W depends primarily on your system requirements and budget. The NZXT stands out with its higher 850W capacity, 80 PLUS Gold and Cybenetics Platinum efficiency, whisper-quiet operation under 15 dBA, and next-gen GPU compatibility. This makes it suitable for enthusiasts, gamers, and professionals seeking a reliable, efficient, and quiet power supply that supports the latest hardware.

Conversely, the JUSTOP Black offers sufficient 700W power for most budget or mid-range builds, with a wide range of connectors and essential safety protections at less than a third of the NZXT’s price. It is an excellent choice for entry-level users or system integrators prioritising cost over the latest certifications and noise performance.

In summary, if you require a power supply with superior efficiency, noise control, and future-ready features and are willing to invest £89.99, the NZXT C850 Gold Core is the better option. However, if you need a functional, cost-effective PSU for a less demanding system at £29.95, the JUSTOP Black 700W delivers solid value.