CORSAIR CX650 80 PLUS Bronze Non Modular Low-Noise ATX 650 Watt Power Supply - U vs JUSTOP Black 700W Power Supply Unit ATX PSU With 120MM Quiet Fan

Power Output and Efficiency

The JUSTOP Black 700W offers a higher wattage rating at 700 watts compared to the CORSAIR CX650’s 650 watts, providing more raw power capacity. However, when it comes to efficiency, the CORSAIR CX650 holds a clear advantage with its 80 PLUS Bronze certification, delivering up to 88% operational efficiency. In contrast, the JUSTOP PSU is rated at around 70% efficiency. This means that despite the JUSTOP’s higher wattage, the CORSAIR unit is more energy-efficient, producing less heat and reducing energy costs over time. For users prioritising power headroom, the JUSTOP’s 700W might appeal, but for those seeking better efficiency, the CORSAIR’s 80 PLUS Bronze rating is a significant benefit.

Build Quality and Design

In terms of design, the CORSAIR CX650 features a compact casing with a length of 125mm, allowing it to fit easily in most modern PC cases. Its black sleeved cables and black powder-coated casing are designed to complement a wide range of PC builds aesthetically. The JUSTOP Black 700W, meanwhile, has a slightly larger footprint at 150mm in width, 85mm in height, and 140mm in depth, making it bulkier but still within standard ATX dimensions. While the JUSTOP’s casing details are less specified, it offers a black finish as well. The CORSAIR’s focus on compactness and sleek sleeving may appeal more to users building a visually coherent and space-optimised system.

Cooling and Noise Levels

Both power supplies incorporate 120mm cooling fans designed for quiet operation, but the CORSAIR CX650 emphasises low-noise cooling more explicitly. Its thermally controlled fan only speeds up under heavy stress, slowing down at lower loads to reduce noise. The JUSTOP also includes a 120mm quiet fan, but it lists a noise level of 40dBA during operation, which provides a measurable reference point. While the JUSTOP’s cooling fan ensures adequate airflow, the CORSAIR’s temperature-responsive fan control promises quieter running at typical load levels. For users sensitive to noise, the CORSAIR solution may offer a more pleasant acoustic experience during everyday use.

Connectivity and Compatibility

Looking at connectors, the JUSTOP Black 700W provides a wide array, including a 24-pin main connector, an 8-pin 12V connector, one PCI-E 8-pin, six SATA, three Molex 4-pin, and one floppy drive connector, reflecting strong compatibility for various components and peripherals. It supports Intel ATX 12V v2.3 and EPS 12V v2.92 standards, making it compatible with most modern motherboards and CPUs. The CORSAIR CX650’s connector details are less explicitly listed, but as a standard ATX power supply, it should cover typical PC requirements. The JUSTOP’s extensive connector count and explicitly stated standard compliance give it an edge for builders needing flexibility and compatibility with a wide range of parts.

Protection and Safety Features

When it comes to protection, the JUSTOP Black 700W is well equipped with a comprehensive suite of safety measures, including over voltage protection, over power protection, short circuit protection, thermal overload cut-off, under voltage protection, and overload protection. It also carries multiple safety certifications such as CE, FCC, UL, and TUV. The CORSAIR CX650’s safety features are not detailed in the provided data, which leaves the JUSTOP clearly ahead in documented protection and compliance. For users prioritising robust safeguarding of their PC hardware, the JUSTOP’s extensive protection features and agency approvals provide reassurance.

Operational Specifications and Reliability

The JUSTOP power supply specifies an MTBF (Mean Time Between Failures) of 50,000 hours, alongside operational temperature limits between 0-40°C, and a hold-up time of 8ms. It also uses active PFC (partial power factor correction) which helps in power quality and efficiency. The CORSAIR CX650’s operational metrics are not detailed in the data provided, but its 80 PLUS Bronze certification implies a reliable performance standard. The JUSTOP’s explicitly stated operational specs and MTBF provide concrete indicators of reliability and durability, crucial for long-term system stability. This transparency might be advantageous for users focused on dependable power delivery under varying environmental conditions.

Price and Value

The JUSTOP Black 700W is priced at £29.95, making it significantly cheaper than the CORSAIR CX650, which is listed at £44.99. For roughly £15 less, the JUSTOP offers more wattage, a wider variety of connectors, and extensive protection features. However, the CORSAIR commands a premium for its higher efficiency rating, compact design, and reputation for quieter operation. The choice here depends on budget and priorities: if raw power and cost-effectiveness are key, the JUSTOP provides strong value, whereas if energy efficiency and quieter running are more important, the CORSAIR justifies its higher price.

Which should you buy?

Choosing between the CORSAIR CX650 and the JUSTOP Black 700W depends largely on your priorities. The JUSTOP supplies 700 watts at a lower price of £29.95, with extensive connectors and well-documented protection features, making it an attractive choice for budget-conscious users who need more power and safety assurances. Conversely, the CORSAIR CX650 offers a more efficient 80 PLUS Bronze rating, a compact 125mm case, and a thermally controlled low-noise fan, all for £44.99. If your build benefits from higher efficiency, quieter operation, and a sleeker form factor, the CORSAIR is worth the premium. Ultimately, the JUSTOP appeals to those prioritising power, safety, and cost, while the CORSAIR suits users valuing efficiency, noise control, and compact design.