Corsair RMi Series RM1000i Fully-Modular Power Supply Review

by - 7 years ago


Introduction & Packaging


The latest range of Corsair PSUs are here at last! The new RMi series is something of an upgrade, offering higher quality components, higher performance and more features compared to the last generation; pretty much everything you would expect from the latest range of anything tech related. Corsair has a rock solid reputation in the system building market, delivering popular and competitive products from CPU coolers, chassis, power supplies and more, so we’re hoping to see them put up a good fight on our test bench today.

The RMi series has a lot in common with the current RM series PSU units, as it still offers all the high-end features you would expect; 80 Plus Gold Certification, fully modular cables, Zero RPM fan modes (up to 40% load), silent component selection (reduced coil whine) and LLC resonant mode topology w/ DC to DC (improves efficiency and voltage regulation). However, the RMi series is setting the bar even higher, with a 7 year warranty, all Japanese capacitors, full output at 50c, a fluid dynamic bearing fan, digital output for additional Corsair Link monitoring capabilities, as well as additional Corsair Link control capabilities, which includes custom fan profiles and the ability to toggle the +12v rail from multiple to single rail modes.

“Corsair RMi Series power supplies are fully modular and optimized for silence and power efficiency. Zero RPM Fan Mode means that the fan doesn’t spin until the power supply is under heavy load, and the fan itself is custom-designed for low noise operation even at high loads. 80 PLUS Gold rated efficiency saves you money on your power bill, and the flat black cables are fully modular so you can enjoy fast, neat builds. The Corsair RMi Series is built with high-quality components, including all Japanese electrolytic capacitors, and is guaranteed to deliver clean, stable, continuous power, even at ambient temperatures as high as 50°C. Users can also install Corsairs Link software to monitor power usage and fan speed. With 650W, 750W, 850W and 1000W models available there is a Corsair RMi power supply suitable for potentially any PC configuration.” – Corsair

Packaging and Contents

The RM1000i offers up, you guessed it, 1000 watts of power. There’s a nice and clear image of the PSU on the front of the box, as well as a quick run-down of the major features on the rest of the packaging, such as the 80 Plus Gold certification and semi-passive cooling design.



In the box, you’ll find the manual, warranty guide, power cable, screws and a few cable ties to help you keep everything neat and tidy.



A Closer Look – Exterior

Power Supply Unit

First impressions of the RM1000i are very good, a really nice design overall and a set of tough fan guard rails on the top, with a pattern on the top panel that matches up with the fan guard rails.


There’s a 135mm fluid dynamic bearing fan in the top, which should provide great cooling performance.


The PSU comes with a fairly understated design, the monochrome design of the label means it should fit into virtually any build easily enough.


On the base, you can see the +12v rail will support up to 83.3A and, of course, that the PSU will handle up to 1000W maximum combined wattage.


One of the coolest features of the RM1000i is the Corsair Link, which can be connected via the proprietary cable or MiniUSB. This will allow you to monitor and adjust fan, voltage and rail configurations from your desktop. There’s also a fan test button, handy for seeing if it actually works if your PSU has been sat in passive mode for a long time. Obviously, there’s a wide range of connections on offer, with 6 x 6-pin, and 6 x 8-pin connectors, as well as the split 24-pin motherboard connector; this is more than enough for most high-end builds and multi-GPU configurations. On the PSU connectors, you’ll notice that the 24-pin is actually a 28-pin connector. These extra wires are “sense wires” which allow the PSU to better monitor and regulate voltage.


A good amount of ventilation around the back, as well as an easily accessible and large power switch.



A great selection of cables overall, with multiple PCI-E connectors and plenty of SATA/Molex for those who have a lot of storage. Also, a very welcome addition is the all black cables, connectors and braiding, which should help you achieve a great looking build. The MOLEX and SATA cables are flat as well which make cable management much easier.




A Closer Look – Interior

The interior of the PSU is remarkably tidy, it’s clear a lot of care and attention has gone into its construction. The manufacturer as per normal with Corsair is CWT. Tried and tested and always first choice for mainstream units for Corsair.


There are two main bulk capacitors in the RM1000i, the largest is rated for 400v, 680uF at up to 105C.




Some nice quality soldering on the AC socket, as well as the EMC/EMI filtering stage.


The modular power connector board, again, all very neat and tidy. You can just make out the extra capacitors which filter the modular connectors for ripple suppression. This allows the ripple/noise to be reduced greatly, even more so when combined with the sense wires.


Here you can see the MCU for Corsair Link. This PCB also features the fan connector for the included 135mm fan.


Four more high-quality Japanese capacitors for the secondary output.


The NR135P fan is of a very high quality and features a fluid dynamic bearing. This should offer even quieter performance that the last generation of Corsair PSUs, especially so thanks to the semi-passive design.



Test Procedure

At eTeknix we take the power supply testing procedure very seriously and have invested a lot of resources into acquiring the appropriate testing equipment. For all power supply reviews we test the power supplies with dedicated power supply testing equipment. This means we are able to get the most accurate results from our testing as opposed to using software benchmarks (such as OCCT) or multi-meter readouts which are broadly inaccurate.


Our test machinery is as follows:

  • Sunmoon SM-5500ATE Active Load Tester (1200W rated)
  • Stingray DS1M12 USB Oscilloscope
  • Voltcraft DT-10L laser tachometer

The eTeknix test procedure involves:

  • Testing each power supply at 20/40/60/80/100% load (with balanced load across all rails) and measuring PFC (power factor correction), efficiency (actual power divided by power “pulled at the wall”) and voltage regulation (deviance from expected voltages of 3.3/5/12 on the main rails).
  • Measuring ripple with an oscilloscope at 20/40/60/80/100% load.
  • Measuring fan speed after a stabilisation period of five minutes at each load scenario using the Voltcraft DT-10L laser tachometer and a reflective strip on the fan.
  • Testing each power supply’s OPP (Over Power Protection) mechanism and seeing how many watts each power supply can deliver before shutting down

Other things to consider are that

  • We recognise that a single yellow 12 volt cable can provide only 6 Amps before overheating (which corrupts voltage regulation and efficiency) and so we used an adequate number of cables for each power supply to ensure there is not efficiency loss from poor cables selection
  • Our Sunmoon SM-5500ATE power supply tester is not capable of testing more than 300W on each of the 12 volt rails so where a power supply provides more than 300W on a 12 volt rail that power is distributed over multiple 12 volt rails on the load tester. For example a power supply with one 12 volt rail supplying 750 watts would be spread equally over three 12 volt rails on the load tester, a power supply with two 450W 12v rails would be spread over four 12v rails on the load tester, two 225W 12v rails for each of the 12v rails on the unit.
  • We use the same time scale and horizontal millivolt scale on our oscilloscope for all ripple tests, that is a 20ms T/DIV (horizontal) and a 0.02 V/DIV (vertical) meaning the scale is from -80mV to +80mV, ATX spec dictates that the 12v rail must fall within 150mv of ripple and the 3.3/5 within 50mv so that scale allows us to include both 150 and 50mV peaks. (Some older PSU reviews use different scales which were later ditched as the visual representation they give is inadequate, in these reviews written measurements are provided only).
  • Deviance is the terminology used to represent the way voltages diverge from the expected values

Efficiency, PFC and Voltage Regulation

Voltage Regulation

To test voltage regulation we load the power supply to five different load scenarios that give an equal spread of load across every single rail. So that means 20% on all rails, 40% on all rails and so on. We then calculate the average deviance of each rail from its expected voltage.


Due to the limitations of our load tester, we had to split the 12v rail across multiple “simulated” rails. The consistency of the power output is very impressive, with very little deviance from 20% load right through till 100% load. The only oddball is the -12V rail, which was 2% above rated, but still well within a suitable margin.

Power Efficiency

Power efficiency is measured by calculating actual supplied wattage divided by the wattage drawn at the wall/plug, multiplied by 100 to give a percentage. We then compare that to the particular 80 Plus certification the company claims to see if it meets that. You can see the 80 Plus certifications below, we always test 230v power supplies.



The RM1000i performed well above our expectations here, with the efficiency performance never dropping below 91%, giving us similar performance to a Platinum rated unit.

Power Factor Correction

Power Factor Correction is the ratio of the real power flowing to the load, to the apparent power in the circuit. The aim of PFC is to make the load circuitry that is power factor corrected appear purely resistive (apparent power equal to real power). In this case, the voltage and current are in phase and the reactive power consumption is zero. The closer the number to one the better as this allows the most efficient delivery of electrical power (Source – Wikipedia).


PFC was very good overall, especially in load scenarios above 40% (non-passive mode).



Noise and Ripple can easily be measured by an oscilloscope. These show how much voltage fluctuation there is on a particular rail. We tested the rail stability of the 3.3 volt, 5 volt and 12 volt rails using an identical time and millivolt scale for all graphs. millivolt ripple is measured by the peak to peak size of the voltage curve.


Sample Ripple Graph

The latest ATX 12 volt version 2.3 specifications state that ripple from peak to peak must be no higher than 50 millivolts for the 3.3 volt and 5 volt rails, while the 12 volt rail is allowed up to 120 millivolts peak to peak to stay within specifications. Millivolt figures are stated to the closest increment of 5 given their variability.

Load (%) 3.3V Ripple 5V Ripple 12V Ripple
20  3.4  4.4  4.2
40  3.4  4.2  5
60  4  5.2  5.8
80  4.2  7  7.8
100  5.6  9.2  11.2

Just like we saw with the RM650i, these test results are incredible! The ripple performance from the new Corsair PSUs is so good, we not only had to retest to make sure the ripple suppression was that good, we also had to check with Corsair that the results were correct; good news is, they were!

3.3 volt @ 100%


5 volt @ 100%


12 volt @ 100%



Over Power Protection and Max Wattage

Power supplies often quote as having various protection mechanisms such and the most important of these is Over Power Protection. In our testing we crank up the power draw until the power supply either shuts down (meaning the OPP mechanism is present and working) or blows up (meaning it is either not present or not working). We then note the maximum power consumption before the power supply shut down (or blew up).


1000 watts is more than enough power for high-end systems, but if you’re overclocking or benchmarking, there’s a risk of even higher power draw spikes. Fortunately, the RM1000i peaked at 1234.4 watts before OPP shut the unit off; more than enough headroom for any spikes in your power usage.


Fan Speed

When testing in a power supply laboratory it is difficult to take fan noise readings as the noise from the Sunmoon test equipment and air conditioning corrupts everything. The next best thing in our circumstances was reading off the fan speed with a tachometer to get an idea for the noise. The ambient temperature during testing held constant at 22 degrees, with 1 degree of variation. Each power supply had a consistent time period of 5 minutes to stabilise between each load scenario. 

In my experience the following general relationships apply between noise levels and fan speeds, though it can vary greatly between the type of fan used.

  • Below 800 RPM – Inaudible/Silent
  • 800 to 1000 RPM – Barely audible
  • 1000 – 1200 RPM – Audible but still quiet
  • 1200 – 1400 RPM – Moderately noisy
  • 1400 – 1800 RPM – Noisy
  • 1800 RPM or higher – Intolerable


Exceptional performance again! Completely silent up to 40% load, and even then the fan was barely audible all the way up to 100% load.


Final Thoughts


The RM1000i isn’t cheap, clocking in at £144.95 from Overclockers UK. Of course, the old saying that you get what you pay for rings true and there’s no doubt that this is a premium quality product.


I’m very impressed by the latest Corsair power supply. It’s got all the features you could want from a high-end PSU, but also brings a few extra features to the table that are more than welcome. You’ve got a huge amount of power to draw from, more than enough for a multi-GPU configuration on an overclocked system. There’s a huge array of power cables, more than enough to hook up all the devices you could fit into an enthusiast grade full-tower chassis. For most people, those two aspects are all they need. However, extras such as the semi-passive/silent design, silky smooth ripple suppression, Corsair link, fully modular cables and excellent efficiency are what makes the RM1000i worth its retail price.

Build quality is superb throughout, from the high-quality cables to the rather simple and understated, but durable metal chassis of the unit. Taking a look at the interior, you can see that the unit has been made with extra care and that no doubt plays a big part in the passive cooling and great efficiency performance. The super quiet performance of the fan is great, even at full load it was surprisingly quiet and under standard day-to-day usage of your system, it’s completely silent.

Corsair Link is certainly a great addition for those eager to use this power supply for overclocking and benchmarking, as it gives you command over rails, voltages, fan profiles and more, allowing you to squeeze every bit of performance from your PSU as well as your system.


  • Fully modular cables
  • Incredible seven-year warranty
  • Exceptional ripple suppression
  • Semi-passive design
  • Fan-test button
  • Corsair Link
  • Great for overclocking
  • Ideal for multi GPU systems
  • Switchable single/multiple 12v rail
  • Sense wires + extra capacitors for voltage and ripple regulation


  • None


  • More expensive than some 1000w units, but you get a lot in return for the extra investment

“The RM1000i delivers impressive performance across the whole range, making it an ideal choice for those who want to overclock, run high-end hardware and more. The build quality, efficiency, fan performance and more are all well above what you would expect, making this one of the best all-round PSUs on the market today.”

Corsair RMi Series RM1000i Fully-Modular Power Supply Review

Corsair RM650i Power Supply Review

Thank you Corsair for providing this review sample.

Article Index

  1. Introduction and Packaging
  2. A Closer Look - Exterior
  3. A Closer Look - Interior
  4. Test Procedure
  5. Efficiency, PFC and Voltage Regulation
  6. Ripple Testing
  7. OPP and Max Wattage
  8. Fan Speed
  9. Final Thoughts
  10. View All

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