Corsair releases new, improved versions of RM750 & RM850 made by CWT
Sunday Apr 19, 2015, 10:59 PM
So far, Corsair's RM line included five models using three distinct designs: the 450-650W models used a custom platform by Corsair & CWT, the 750/850W models used a custom platform by Chicony, and the 1000W unit used another custom design by Corsair and CWT.
The 750/850W units in particular received some bad comments from people on the Internet, who complained about the capacitor choice, as well as a temperature issue that was discovered and promptly fixed a few weeks after the RM series appeared on the market.
In the last few months it became apparent that Corsair is going to phase out the 750 and 850W models. Whether Corsair wanted it or not, the hints could be seen being dropped in various documents and files, and lately some lucky shoppers have started receiving the first samples of the refreshed units.
Corsair RM850 by CWT
Photo courtesy of JonnyGuru
These two models are now manufactured by CWT. The platform doesn't have a public name, because it's a unique job by Corsair engineers and CWT's specialists working together. You an definitely see similarities between this design and the ones used in other Corsair products: something similar to it first appeared in the RM1000, then matured in the HXi series, and now we see another sibling of this idea in the new RM models.
The most noticeable improvements over the older versions by Chicony are:
- Completely new platform featuring an LLC resonant converter and improved PCB layout;
- Slightly lesser ripple;
- Nippon Chemi-Con primary capacitors;
- Nippon Chemi-Con secondary side electrolytic capacitors;
- APAQ (Japanese) secondary side polymer capacitors;
- Much more room to breathe for the caps
Main complaint from the old series - the secondary side capacitors - is gone: the new versions use only the highest quality Japanese caps instead of the questionable Ltec ones. They do their job really well as you can see on the ripple scope shots in Wolf's review. If you're like the many people who only look at the brand of brand of the capacitors used in the power supply, then you can safely say that the new RMs are built with the highest quality materials.
The performance side of things sees improvements, too: read the review for exact values.
Here's a comparison table of the internals of both PSUs. Unfortunately not every important part has been identified by reviewers, but there's still a lot of data to look at.
| Corsair RM850 |
| Corsair RM850 |
|Fan:||Corsair NR135L (12 V, 0.22 A, rifle bearing)|
|Topology:|| Full bridge ||Half bridge|
| LLC: ||No||Yes|
| Secondary side regulation: || Minor rail DC-DC converters on main PCB daughterboard |
| Transient filter |
|Components:|| 4x Y cap, 2x X cap, 3x coil ||4x Y cap, 3x X cap, 2x coil |
| Primary side |
| Bridge rectifier ||2x unknown || 2x unknown |
|APFC:||3x Infineon IPP6R190E6, CREE C3D08060A boost diode|| 2x unknown |
|Switchers:||4x Infineon IPP50R190CE||2x Vishay SiHG20N50C|
| Main capacitor: ||Panasonic 420 V, 560 μF, 105°C || 2x Nippon Chemi-Con |
KMR series, 400V, 330 μF, 105°C
|PFC/PWM controller: ||Champion CM6802|| Infineon ICE2HS01G PWM |
Infineon ICE3PCS01G PFC
|Resonant controller:||N/A||Infineon ICE2HS01G|
| Secondary side |
|+12V:||6x Infineon BSC028N06NS|| 6x Sinopower SM4021NAKP |
| +5V & +3.3V: ||unknown || 6x ETC M3006D |
PWM controller: Anpec APW7159
|Capacitors:||+12V: Ltec LXY series, 105°C |
Minor rails: Taicon, 105°C
Modular board: Ltec, LXY & LZG series, 105°C
| Main PCB: Nippon Chemi-Con KZE series, 105°C |
Daughterboard: NCC 105°C (electrolytic), APAQ (polymer)
Modular board: APAQ (polymer)
|Protection circuit:||Unknown |