The Chieftronic PowerUp 850 W achieves satisfactory overall performance and has very low average noise output, even to where I am worried about its reliability over the long run. It doesn't use high-quality caps on its secondary side, and the bulk cap has a low temperature rating as well. Keeping capacitors at increased operating temperatures is not a good idea. Thankfully, CWT used many polymer caps on the secondary side, which are way more tolerant of high operating temperatures. Nevertheless, the very similar DeepCool GamerStorm DQ-M V2L, which uses Japanese caps in its secondary side, has a notably more aggressive fan-speed profile, providing more airflow for lower operating temperatures.

The average efficiency is satisfactory, and the same goes for the efficiency of the 5VSB rail. That said, efficiency at light and super light loads could be higher since the new ATX 2.52 specification asks for more than 70% efficiency with 2% load. It would be nice to see support for Alternative Sleep Mode (ASM), which would make this PSU more future-proof. Performance of the APFC converter is very disappointing—it needs tuning to provide higher power factor readings, especially with 230 V.

Another thing that bothered me is the single EPS cable with two connectors. This is not an elegant solution for a high-end mainboard requiring two EPS connectors. A CPU could be so power-hungry as to nearly fully utilize both EPS connectors, which would make the connector on the PSU melt. They should install each EPS connector on a dedicated cable. Moreover, I am not a fan of two PCIe connectors on the same cable, either. Graphics cards like the RTX 3080 can pull more than 300 W from these connectors, so you will have substantial voltage drops or even melted gauges. When brands provide cables with dual PCIe connectors, there should be a warning not to use both at the same time with power-hungry graphics cards.

All in all, I cannot say that the Chieftronic PowerUp 850 W left the best impressions on me. With some changes, it could be a lot better. I would start by replacing all caps with higher-quality ones and putting each EPS connector on its own cables. I would also check the fan-speed profile, which keeps airflow at low under even highly stressful conditions.