Corsair RM750x PSU Review
In a sudden move, Corsair recently released another PSU series with 80 PLUS Gold efficiency. The RMx models come in five versions with capacities ranging from 550 W to 1000 W. In short, these PSUs are a budget version of the RMi models, designed for users who want high performance without paying the extra cost of a digital circuit. Since the RMx units are based on the same platform that equips the RMi PSUs, they offer good performance along with silent operation. In order to achieve high reliability in these PSUs, Corsair made no compromises in build quality; only Japanese capacitors were used, which last longer than Taiwanese and Chinese versions, and most importantly, they age much slower.
The main differences between the more expensive RMi models and the RMx versions are seen in the latters' lack of a digital interface board and fan test button (which can come very handy on a semipassive PSU). Additionally, the RMx models use a different fan, with a Rifle bearing, which is of lower quality than what the RMi models use. These use fans with fluid dynamic bearing (FDB), which is considered the best bearing available today. Another significant difference is the single +12V rail that the RMx units feature. In the RMi PSUs, the user can choose between single and multi +12V modes through the Corsair Link software.
The following table provides comparisons among the RM, RMi and RMx units.
| Header Cell - Column 0 | RM | RMx | RMi |
|---|---|---|---|
| 80 Plus certification | Gold | Gold | Gold |
| Cable system | Fully Modular | Fully Modular | Fully Modular |
| Capacitors | Japanese Primary (APFC) | 100% Japanese | 100% Japanese |
| Max Cont. Output Rating | 40°C | 50°C | 50°C |
| Fan | 135mm Rifle Bearing | 135mm Rifle Bearing | 140mm FDB |
| Corsair Link Support | Basic: Monitor fan & +12V load | None | Full |
| Wattage Range | 650, 750, 850, 1000 | 550, 650, 750, 850, 1000 | 550, 650, 750, 850, 1000 |
| Warranty (Years) | 5 | 7 | 7 |
| MSRP | RM650 - $129.99 RM750 - $139.99 RM850 - $159.99 RM1000 - $189.99 | RM550x - $109.99 RM650x - $119.99 RM750x - $129.99 RM850x - $149.99 RM1000x - $179.99 | RM650i - $139.99 RM750i - $149.99 RM850i - $169.99 RM1000i - $199.99 |
Specifications
The PSU features Gold efficiency, and it can deliver its full power continuously at up to 50 degrees Celsius, like every well-performing PSU should. On top of that, it is Haswell-ready, meaning that it employs independent regulation circuits for the minor rails, and in this case, two DC-DC converters are used. In the section on protection features, we see all of them, since Corsair wanted to provide increased reliability and safety on this platform.
As we already stated, contrary to the more expensive RM750i model, this unit comes with a Rifle bearing fan. Although it is no match for an FDB, it will still get the job done, and it offers good enough reliability. Rifle bearing fans are basically an enhanced version of the plain sleeve bearing ones, offering significantly longer lifetimes, comparable to the lifetimes of ball-bearing fans.
To lower noise output at light and mid loads Corsair included a semi-passive mode, which will also increase the fan's lifetime. Finally, this unit is on the large side, at 18-centimeters long, while its price looks decent given its features.
Power Specifications
| Rail | 3.3V | 5V | 12V | 5VSB | -12V | |
|---|---|---|---|---|---|---|
| Max. Power | Amps | 25 | 25 | 62.5 | 3 | 0.8 |
| Watts | 150 | 750 | 15 | 9.6 | ||
| Total Max. Power (W) | 750 |
There is a single +12V rail, which can deliver enough amperes to support a couple of high-end VGAs. The minor rails are very strong as well, while the 5VSB rail is a little stronger than the average, with 3A max-current output.
Cables & Connectors
| Modular Cables | ||
|---|---|---|
| Description | Cable Count | Connector Count (Total) |
| ATX connector 20+4 pin (610mm) | 1 | 1 |
| 4+4 pin EPS12V (650mm) | 1 | 1 |
| 6+2 pin PCIe (600mm+150mm) | 2 | 4 |
| SATA (400mm+100mm+100mm+100mm) | 1 | 4 |
| SATA (550mm+100mm+100mm+100mm) | 1 | 4 |
| Four-pin Molex (450mm+100mm+100mm) | 1 | 3 |
| Four-pin Molex (450mm+100mm+100mm+100mm) | 1 | 4 |
| FDD Adapter (+100mm) | 2 | 2 |
A very interesting feature of the RMx units comes in the modular cables they use, which are similar to those of the RMi models and which Corsair describes as Type 4 cables. Polymer capacitors are installed on the +12V, 5V and 3.3V wires of the ATX cable and on the +12V wires of the EPS and PCIe cables, providing extra ripple filtering. On top of that, the ATX cable plugs into the PSU's modular interface through 28 pins instead of the usual 24 pins, with the extra four pins acting as sense wires. The use of sense wires allows for a very tight load regulation, Corsair claims, which is a key performance feature for any high-end PSU.
Power Distribution
Since this PSU features only a single +12V rail, we do not have anything to say about its power distribution.
MORE: PSUs 101: A Detailed Look Into Power Supplies
MORE: How We Test Power Supplies
MORE: All Power Supply Articles MORE:
Power Supplies in the Forums
