Introduction
Corsair has revamped its RM line, adding the letter "i" to it, which highlights the use of a more advanced digital interface compared with the previous generation. Today we will test how the RM750i 750 Watt power supply fares against the competition.
Corsair's RM line includes the most silent PSUs money can buy today and features a digital interface, which gathers limited information regarding the PSU's status and operation. Since digital circuits are better than analog ones, Corsair decided that it was time to introduce its new RMi line, which includes four models with 650 W, 750 W, 850 W and 1 kW capacities. The major differences between the RM and the new RMi series are:
- Seven-year warranty instead of five.
- Exclusive use of Japanese capacitors.
- Fluid Dynamic Bearing (FDB) fan instead of the Riffle-bearing fan that the RM units have.
- A more advanced digital circuit that allows the monitoring of power in/out, efficiency, output voltages and temperature, as well as DC load and fan speed.
- The new digital circuit provides the ability to create a custom fan profile and convert the PSU's +12V rail from a single one to multiple +12V rails.
All of the above new features look very interesting, and we have high expectations for the new RMi units, especially since they are built by Channel Well Technology, an OEM that Corsair has enjoyed a long and satisfying relationship with. The PSU undergoing tests today will be the RM750i unit, which, thanks to its mid-level capacity, addresses a significant portion of users. With four PCIe connectors, the RM750i can support up to two VGAs with double PCIe sockets each, and Corsair promises a very silent operation under all conditions, which will make users happy, especially those who dislike noisy system components. What we don't want to see is a very high temperature threshold for the fan's activation, which was the case in previous RM units. However, the new RMi PSUs allow users to create custom fan profiles that better suit their needs and systems.
Specifications
Corsair deliberately kept the same efficiency rating as the previous RM line. Increasing it from Gold to Platinum would have made the new RMi units compete directly with the HXi line, Corsair's higher-end PSUs. This is something that PSU companies try to avoid, especially ones with large product portfolios like Corsair. A crucial update to the new units was the 10 degree Celsius increase in the maximum operating temperature at which full power can be delivered continuously. This means that the platform has been upgraded to withstand increased heat and that it is more reliable compared with the older one. This is also reflected in the addition of two years to the warranty period, to seven years.
The RM750i PSU comes with all available protection features, is fully modular and uses the same FDB fan as the other high-end Corsair units. Thanks to its quality bearing, the NR135P fan will last for a long time; on top of that, it is very silent, even at higher speeds. Moreover, it is supported by a highly relaxed fan profile and a semi-passive mode operation.
Power Specifications
| Rail | 3.3V | 5V | 12V1 | 12V2 | 12V3 | 12V4 | 12V5 | 5VSB | -12V | |
|---|---|---|---|---|---|---|---|---|---|---|
| Max. Power | Amps | 25 | 25 | 40 | 40 | 40 | 40 | 40 | 3 | 0.8 |
| Watts | 150 | 750 | 15 | 9.6 | ||||||
| Total Max. Power (W) | 750 |
The RM750i PSU comes with multiple +12V rails with the OCP set at 40 A for each one of them, in order to avoid problems with energy-hungry VGAs. The minor rails are very powerful for a contemporary PSU, while the 5VSB rail is a little stronger than the average.
| 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 |
Up to 62.5 A can be delivered in the single +12V rail mode, thus the PSU's total capacity can be handled by the +12V rail alone. This is a feature typically seen in modern PSUs that use DC-DC converters for the generation of the minor rails.
Cables And Connectors
| Modular Cables | ||
|---|---|---|
| Description | Cable Count | Connector Count (Total) |
| ATX connector 20+4 pin (610mm) | 1 | 1 |
| 4+4 pin EPS12V (660mm) | 1 | 1 |
| 6+2 pin PCIe (610mm) | 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 |
| C-Link USB Cable (800mm) | 1 | 1 |
| C-Link I2C Cable (800mm) | 1 | 1 |
For a 750 W PSU, the number of cables provided is sufficient for the majority of users; however, we would have liked to have seen an extra EPS cable. Normally, a PSU of this category comes with two EPS cables, or at least a single EPS and one ATX12V (4-pin) cable, in order to support high-end mainboards. The number of SATA and peripheral Molex connectors is adequate. The cable bundle also includes two Corsair Link cables, with one of them hosting a mini USB connector. Finally, the PCIe cables consist of thicker 16AWG wires, while the rest of the connectors use the standard 18AWG gauges.
Power Distribution
According to Corsair, when the PSU operates in multi +12V mode -- which is selected by default -- the Over Current Protection (OCP) is set to 40 A on each of the 8-pin modular connectors (for PCIe and EPS cables). The same OCP trigger point also applies to the 24-pin ATX connectors, and all 6-pin modular connectors are fed by a virtual +12V rail with 40 A OCP as well. What this means is that power distribution is optimal since all PCIe and EPS cables are fed by dedicated +12V rails and the same applies to the 24-pin ATX connector.
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