Corsair RM1000x 1000 Watt 80 PLUS Gold Fully Modular Power Supply Review

by - 4 years ago


Introduction & Packaging

Corsair RM1000x 1000 Watt 80 PLUS Gold Fully Modular Power Supply Review

Corsair have been known to produce some of the best power supplies in the business and today, they look set to continue that trend with the release of their high-end RM1000x. Not everyone needs 1000w of power, of course, but when you do, it’s likely that you’re also the kind of system builder who demands the best performance from your components. Previous high-end PSUs from Corsair have reaped some of the best results we’ve ever seen, with ripple so low we thought there was an issue with our testing equipment, so to say we’re a little eager to see what this one can do would be quite the understatement.

“Corsair RMx series power supplies give you extremely tight voltage control, quiet operation, Gold-certified efficiency, and a fully modular cable set. Built with all Japanese 105°C capacitors, they’re a great choice for high-performance PCs where reliability is essential. 80 PLUS Gold efficiency reduces operating cost and excess heat, and Zero RPM fan mode ensures virtual silence at low and medium loads. And, the fully modular DC cables make builds and upgrades easy, with clean, great-looking results.” – Corsair

Equipped with all the usual safety features you would expect, as well as 80 Plus Gold efficiency, all Japanese capacitors, a ZeroRPM mode, a powerful 135mm fan, fully modular cable design and more, the RM1000x certainly ticks all the right boxes and to sweeten the deal, Corsair has given it a 7-Year warranty! That last part fills me with a lot of confidence.


1000W is a lot of power, more than enough to power an extreme workstation or gaming system with enthusiast overclocks and multiple graphics cards. As you can see, that 12V rail can push a very mighty 83.3A, more than enough power for Screenshot_19

The packaging is very nicely designed, with a big and clear shot of the PSU on the front and that stand-out black and yellow Corsair branding.


Around the back, a quick technical rundown of the efficiency, hybrid fan mode and connectors.


There’s quite a lot of stuff in the box, with a durable protective bag for all the modular cables, a soft bag with the PSU inside, heavy-duty power cable,  cable ties, screws, and all the usual documentation.



A Closer Look – Exterior

The build quality on this PSU is excellent. It has a good weight to it and the outer casing looks and feels durable. There’s a big fan grille on the top, with a lot of ventilation for the built-in Corsair fan.


On the base, just a large specifications sticker.


As you can see, it has got a mighty 83.3A on the single 12V rail; you’ll never have to worry about a lack of power for your CPU/GPUs!


This is where thing get interesting, as there is a huge array of connectors on offer here. With six peripheral/SATA connectors, as well as six 6+2 pin PCI, a 4+4 for the CPU, and the motherboard 24-pin, you’re not going to be short of connectivity, even on a multi-GPU configuration.


Down the left and right-hand sides, a stylish RM1000x logo


Around the back, there’s a lot of ventilation that runs right to the edges, giving as much area as possible to exhaust heat from the unit. This is going to help greatly with the zeroRPM fan mode and help keep everything cool and silent as often as possible.



there are a lot of cables to contend with here, but you’ll be glad to know that all the peripheral cables are flat, meaning routing them will be an easy task. There’s a huge amount of SATA and Molex connectors too, so huge banks of storage should prove easy to connect.


The heavy-duty cables for the motherboard and PCIe devices are thicker, but come with all black cables, black braiding and black connectors, so they should blend nicely into your build. They’re all very high quality too, so should last you many years of system rebuilds.



A Closer Look – Interior

This is a powerful unit, so there’s a lot of hardware to contend with in here. Everything looks nicely spaced out though and I’m immediately impressed with how little cabling there is too, as this will no doubt help improve the overall airflow.


There are two main bulk capacitors here, a 400V 470uf and a 400v 680uf, both rated for 105w and both Japanese made; I’m expecting this PSU will pull well beyond its 1000w rating with relative ease.


There are high-quality caps everywhere in this unit, as well as extra caps to help provide clean and stable voltages to all of the available outputs. What little wiring there is in here is very well secured and comes with thick shielding and are all very well secured; build quality is certainly not an issue here.


Any secondary boards are mounted vertically, helping further enhance the airflow, and there’s a small heat sink here too to help keep the main hardware as cool as possible, even when running passively.


The soldering on the rear board for the connectors is neat and tidy too, and there str even more capacitors on each port to help keep those voltages steady.


A small board here has the hardware for the fan control system, as well as a 2-pin header for the fan; naturally, we’ve got the fan unplugged at the moment.


The AC line in and filtering stage looks nice and durable too, with clean solder and thick shielded cables.


Finally, we have the NR135L fan, a 135mm fan of Corsairs own design and that should provide us with great airflow and low noise/RPM.



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.


Really tight regulation here, with all the major voltages being less than 1% away from spec, and in most cases, even closer than that. The -12v rail is a little hot, but is really no cause for concern, these are very good voltages overall and should provide you with a very stable system.

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 RM1000x falls perfectly into the 80 Plus Gold efficiency rating, giving good results across the full load range.

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).


The PFC performance on this unit is exceptionally good, some of the best results we’ve ever seen and once again improving on the fantastic performance of previous high-end Corsair PSUs.



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  2.2  3.6  4.2
 40  3  4.4  5.4
 60  5.3  5.6  5.8
 80  5.3  6.6  7.8
 100  6  8.2  12.6

Just like we saw with the voltage regulation and PFC, the ripple performance is spectacular, easily some of the best scores we’ve seen and a sure sign that this unit can offer up clean and stable power delivery.

3.3 volt @ 100%

rm1000 3v

5 volt @ 100%

rm1000 5v

12 volt @ 100%

rm1000 12v


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).


Again, another fantastic result for this unit, as we managed to pull over 250W extra power from it before the OPP kicked in; more than enough to deal with any big power spikes.


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


At 40% load or below, the fan stopped spinning entirely, making this unit completely silent. However, even at max load, the fan didn’t pass 1000RPM and was still very quiet overall.


Final Thoughts


The Corsair RM1000X was never going to be cheap, it is a high-end, high-power and 80 Plus Gold rated unit after all. You can pick one up from for £149.95 Inc Shipping, although most  major retailers have them in stock for around the same price.


The latest power supply from Corsair is easily one of the best to date. It delivers big performance that’s going to give their competition a serious run for their money at this price range. In terms of features, it’s certainly well equipped, with a hybrid fan mode that keeps the fan at 0RPM in low-load scenarios, so when you’re working it’ll be virtually silent. The cables design is fully modular, which is going to make your cable routing a whole lot easier while I also appreciate that Corsair has gone with black cables, black braiding and black connectors, as it really helps unify the aesthetics.

Equipped with excellent quality all Japanese 105c rated capacitors, the power delivery is some of the best we’ve seen. The ripple levels are so low that they make a mockery of the ATX 12 volt specifications, which is obviously no bad thing, as it means your system is getting clean power delivery. This is further backed up by the near perfect PFC and the tight voltage regulations, something that is sure to put a smile on the face of anyone overclocking, as stable voltages can translate to more stable clocks.

Build quality is nice and robust and the overall design is certainly pleasing to the eye, meaning it should blend easily into virtually any system build. It is a little pricey, but given that it comes with such impressive performance figures, offering up 1000W of power (and 1250W before OPP kicked in), and comes backed up with an impressive 7-year warranty, we think it’s worth every single penny.


  • Robust build quality
  • Fully modular cables
  • All black cables/connectors
  • High-quality components
  • Zero RPM fan at low loads
  • Excellent OPP performance
  • Extremely low ripple
  • 80 Plus Gold Efficiency
  • 7-year warranty


  • None
Corsair RM1000x 1000 Watt 80 PLUS Gold Fully Modular Power Supply Review

Corsair RM1000x 1000 Watt 80 PLUS Gold Fully Modular 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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