A Look Inside & Component Analysis

Before reading this page, we strongly suggest a look at this article, which will help you understand the internal components of a PSU much better. Our main tool for the disassembly of the PSU is a Thermaltronics TMT-9000S soldering and rework station. It is of extreme quality and is equipped with a matching de-soldering gun. With such equipment in hand, breaking apart every PSU is like a walk in the park!


Like the RM850, this unit is also made by Chicony. We don't understand why Corsair assigned these two units to Chicony instead of CWT making all the other RM PSUs, but they apparently had their reasons. CWT was most likely too busy to built every RM unit, which had Corsair reach out to another manufacturer for assistance, or they didn't want to rely on one manufacturer for this series. Either way, the final result is good and almost up to the standards we are used from Corsair. Our only complaint is the choice of caps in the secondary side. They are not of the best quality, but Corsair seems to trust them since they cover these units with a pretty long five year warranty.


The heatsinks of the RM750 are very large for a Gold unit that normally only needs a limited amount of heat dissipation. These will, however, help the PSU cope with its semi-passive operation better. The metallic plate on which the main PCB is seated will also provide this unit with some additional heat dissipation. As for the platform/design, it is definitely not cutting edge, but it still utilizes a unique design in its primary side since we haven't seen anything similar so far, with two parallel pairs of mosfets as main switchers. There is also no heatsink in the secondary side, which does remind us of CWT's PUQ platform.


The first part of the transient filter starts right at the AC receptacle and only includes a pair of Y caps. The second part is on the main PCB and consists of three CM chokes, two Y and two X caps, and an MOV (Metal Oxide Varistor).


The single bridge rectifier is bolted to a large heatsink. We unfortunately couldn't identify the rectifier without desoldering it, which we weren't in the mood for. The X cap in front of the bridge rectifier doesn't belong to the transient filter, but plays the role of the PFC input cap.


In the APFC circuit, three mosfets and a CREE C3D08060A boost diode are used. The bulk cap is provided by Nippon Chemi-Con (420 V, 470 μF, 105°C, KMQ series).


The combo PFC/PWM controller is located on a small vertical PCB that is surrounded by heatsinks. It is a Champion CM6802 IC, an upgraded version of the omnipresent CM6800 usually found in Bronze efficiency PSUs.


Two pairs of Infineon IPP50R190CE fets are used as main switchers. Paralleling the fets' current halves throughput, which greatly restricts energy losses. This is an ingenious, not-so-expensive design, and we wonder why this is the first time we see it in a desktop PSU.


We had to remove the main transformer because it blocked the view to crucial components.


There are no heatsinks in the secondary side, at least in the classical sense. All fets rectifying the +12V rail are instead located on a vertical PCB with three bus bars. The latter provide earth and cooling. The aforementioned fets are six Infineon BSC028N06NSs. The RM850 uses exactly the same type and number of fets. On top of these fets is an APE6019 synchronous rectifier (SR) driver IC.


The same PCB holding the +12V rectifying circuit also holds the two DC-DC converters generating the minor rails. Two Taicon caps are used by these converters, and we wonder why Corsair didn't use polymer ones instead, especially since the unit will work in fanless mode most of the time. The minor rails transfer off this PCB and to the modular one via a significant number of short cables, which makes sure they suffer from the lowest energy losses possible.


The filtering caps in the secondary side are provided by Ltec—not our favorite choice. We think Corsair should use higher quality caps here since this unit usually runs in passive mode. Time will tell if they were right to trust Ltec caps or whether many units will be RMAed instead.


This daughter board hosts the protections IC, which is well hidden by numerous cables that make identifying an impossible task.


The front of the modular PCB has more Ltec caps for some extra ripple filtering.


Soldering quality is above average, that's for sure, but it still isn't up to the levels we are used to from Corsair products. However, its soldering quality will not effect performance.


The fan is the same as in the RM850, and was according to Corsair built with silence in mind. It uses rifle bearings, an enhanced type of the plain sleeve bearings, and its model number is NR135L (12 V, 0.22 A). It really is very quiet at even high speeds it will hardly reach under real-life conditions, especially if the RM750 is installed in a case with good airflow.