Along with the Corsair RM750, the XPG Core Reactor 750 is the second power supply in this Wattage category supporting the new and tough requirements that the ATX spec sets: higher than 70% efficiency with 2% of the max-rated-load (15W) and a within 100-150ms Power-Ok delay with a lower than 150ms Power-on time. Those requirements require major hardware changes that cost money, and this is why the PSUs that are fully compliant with the newest ATX spec cost more.
The XPG Core Reactor 750 has high performance and also has very low and often silent operation. XPG loaded with a great number of modular cables and connectors, including two EPS, six EPS, and twelve SATA. With such an amount of connectors, you won't face any compatibility issues and on top of that, the PSU's max power will be easily delivered without notable voltage drops. Finally, the build quality is great and XPG used good and expensive parts, including an FDB fan and fully Japanese capacitors, so the PSU will easily outlive the long warranty.
As of this writing, the XPG Core Reactor 750 costs ten dollars more than the RM750x, which might not be fully compatible with the new requirements of the ATX spec, but it achieves higher overall performance, and is even quieter. Nonetheless, if you do care about high efficiency at super-light loads and also require compatibility with alternative sleep mode, the choices in the 750W category are limited to XPG's offer and the Corsair RM750. The latter has almost the same performance as the Core Reactor unit, and it costs around $20 less but uses less-reputable components, though with the same 10-year warranty support.
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Disclaimer: Aris Mpitziopoulos is Tom's Hardware's PSU reviewer. He is also the Chief Testing Engineer of Cybenetics and developed the Cybenetics certification methodologies apart from his role on Tom's Hardware. Neither Tom's Hardware nor its parent company, Future PLC, are financially involved with Cybenetics. Aris does not perform the actual certifications for Cybenetics.