Corsair HX850 PSU Review
It would appear that Corsair has ditched Yate Loon and went with a Hong Hua fan this time instead. The Hong Hua fan features a dual ball bearing and may reach a maximum rotational speed of 2800RPM if deemed necessary. Other than that, it is your regular black frame and blades fan, without any form of lighting.
The OEM behind the HX850 is CWT, a well-known designer and manufacturer of high performance power supplies, with most of their designs being easily recognizable by their green transformers. The lack of large heatsinks may confuse users into thinking that there is no primary and secondary side and that HX850 is based on some sort of state-of-the-art design. This is not the case here as the topology is based on a synchronous converter, which may be expensive but also used by several other designers; however, Corsair managed to improve the efficiency of their unit to the point that the secondary side components, namely the entire synchronous converter itself, hardly needs any cooling at all.
The filtering stage begins at the back of the A/C receptacle, with two Y-type capacitors. Two more can be found on the PCB, alongside two X-type capacitors, two chokes and a surge suppressing MOV. There is also one classic glass fuse which could prevent damage to more vital components from at least a few dangerous electric phenomena. The heatsink which holds the bridge rectifiers is the best one found inside the HX850.
The primary side of the HX850 is a little strange; the two APFC transistors have been installed on a plain heatsink, while a diode which completes the APFC circuit is installed on a smaller, dented heatsink. Why the designer did not install a single better heatsink for all of the APFC components, we will never know, although it most likely was due to PCB space restrictions. The two large primary side switching transistors can be seen on the plain heatsink next to the transformer. Corsair went with two Nippon Chemi-Con 420V/330μF capacitors at the primary side of the HX850.
The secondary side circuit, which is the synchronous rectifier, is almost entirely present on the vertical PCB on the other side of the transformer. As we mentioned before, Corsair enhanced the efficiency of this design so much that the rectifier requires no extra cooling. The rectifier generates the main 12V line and the 3.3V/5V lines are being derived from DC to DC conversion circuits. The capacitors at the secondary side of the HX850 are also provided by Nippon Chemi-Con, making this unit an all-Japanese affair.