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Corsair RM1000x PSU Review (2021 80+ Gold)

Rating: 8.0.

Today we take a look at one of the newest power supplies to hit our labs, the Corsair RM1000x – a fully modular 80 Plus Gold rated unit featuring high quality Japanese capacitors. These units target the mainstream enthusiast hardware gamer, with 550W, 650W, 750W, 850W and 1000W capacities available.

The Corsair RMx Series feature a magnetic levitation (ML) fan which has been specifically tuned for use in a power supply. Earlier versions of these ML fans were first used in Corsair power supplies back in 2016. Corsair claim lower noise levels with these magnetic levitation bearing models, as well as high performance.

The 2021 RMx models have a new version of the Levitation fan with lower fan noise throughout the entire range. The power supplies also feature a zero RPM mode to help reduce fan noise under lower load conditions.

All models are a compact size, measuring 160mm long, except the 1000W model we have today for review, which is 180mm in length.

Key Features:

  1. Magnetic Levitation Fan: Utilizes magnetic levitation bearings and custom engineered rotors for high performance and low noise.
  2. 100% All Japanese 105°C Capacitors: Premium internal components ensure unwavering power delivery and long-term reliability.
  3. Modern Standby Compatible: Extremely fast wake-from-sleep times and better low-load efficiency.
  4. Zero RPM Fan Mode: At low and medium loads the cooling fan switches off entirely for near-silent operation.
  5. Fully Modular: Only connect the cables your system needs, making clean and tidy builds easier.
  6. Compact Size: A 160mm-long casing ensures an easy fit in almost all modern enthusiast PC cases.
  7. 80 PLUS Gold Certified: High efficiency operation for lower power consumption, less noise, and cooler temperatures.
  8. Ten-Year Warranty: Your guarantee of reliable operation that will last across several system builds.

The Corsair RM1000X ships in a bright yellow box with a high resolution picture of the power supply on the front. There is an 80 Plus Gold logo bottom right along with an image indicating the 10 year warranty.

The power supply itself ships in a clear plastic wrap with two foam pads on either side.

Inside Corsair supply some cable ties, a regional specific power cable and the modular cables. There are mixture of flat and sleeved cables supplied as detailed in the table above.

The power supply is nicely finished – with a neutral colour scheme set to fit into any themed system build.

The top of the power supply is home to the large fan, which we will look at closer when we open the unit shortly.

One side of the power supply is vented to aid with airflow. There is a power connector and switch beside the panel. The other side of the unit is home to the modular bay, clearly labelled to ensure easy installation of cables.

We can see the power supply is able to deliver 83.3A to the +12V rail if needed. Both +3.3V and +5V rails can deliver 20A for 150W of the load.

Inside we can see the NR140ML (12V, 0.27A) fan is installed with several plastic panels to direct airflow over specific components underneath.

CWT are the OEM of choice for this power supply – a long term partner for Corsair in the power supply sector. The CWT design is clean throughout with several substantial heatsinks to ensure components are adequately cooled. Soldering quality is fine throughout with no real noticeable issues.

The primary capacitors are 105c Japanese – specifically Nippon Chemi Con, from the KMW series. These are rated at 400V 680uF and 400V 470uF for a total of 1150uF. The power supply offers OCP, OPP, OTP, OVP, SCP and UVP protection.

Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load.

We test ambient temperatures at 35c in our environment to greater reflect warmer internal chassis conditions.

We use combinations of the following hardware:
• SunMoon SM-268
• CSI3710A Programmable DC load (+3.3V and +5V outputs)
• CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa)
• Digital oscilloscope (20M S/s with 12 Bit ADC)

• Variable Autotransformer, 1.4 KVA

We test in a single +12V configuration.

DC Output Load Regulation

Combined

DC Load

+3.3V
+5V
+12V
+5VSB
-12V
A
V
A
V
A
V
A
V
A V
100W
0.90
3.34
0.90
5.01
7.35
12.05
0.50
5.02
0.20
-12.03
200W
1.60
3.34
1.64
5.01
15.13
12.04
1.00
5.02
0.20
-12.02
500W
3.20
3.34
3.25
5.00
38.60
12.02
1.50
5.01
0.20
-12.02
750W
4.03
3.33
4.16
5.00
58.53
12.01
2.00
5.01
0.30
-12.02
1000W
5.45
3.33
5.51
5.00
78.13
12.00
2.50
5.01
0.30
-12.02

The load regulation of this power supply is stellar, with all rails exhibiting very minor fluctuation under load.

Corsair RM1000x PSU Maximum Load
1170W

We managed to get another 170W from the power supply before the protection circuitry kicked in. The supply was undamaged and it was ready to fire up again when we were a little more sensible with the load.

Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.

Cross Load Testing +3.3V +5V +12V -12V +5VSB
A V A V A V A V A V
885W 2.0 3.34 2.0 5.01 72.0 12.00 0.2 -12.01 0.50 5.02
240W 20.0 3.32 24.0 4.99 2.0 12.05 0.2 -12.01 0.50 5.01

The Corsair supply handled the Cross load tests without any concerns.

We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum. ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.

ATX12V Ver 2.2 Noise/Ripple Tolerance
Output
Ripple (mV p-p)
+3.3V
50
+5V
50
+12V1
120
+12V2
120
-12V
120
+5VSB
50

Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load +3.3V +5V +12V 5VSB
100W 5 5 5 5
250W 5 5 10 5
500W 5 5 15 5
750W 5 5 20 5
1000W 10 5 25 10

Ripple noise suppression is impressive, hitting 5mV and 10mV from the +5v and +3.3V rails respectively. The +12V rail peaks at 25mV, which is an excellent result.

Efficiency (%)
100W
88.9
250W
90.7
500W
92.3
750W
91.3
1000W
90.2

The efficiency results are excellent, peaking at 92.3% at close to 50%. This drops to 90.2% efficiency at full load. These are solid results for a 80 Plus Gold certified unit.

We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

Today to test the Power Supply we have taken it into our acoustics room environment and have set our SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa) one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.

As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.

KitGuru noise guide

10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refrigerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 Player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum

Noise (dBA)
100W
<28.0
250W
<28.0
500W
30.2
750W
31.9
1000W 35.2

The large fan does not make much noise until the last 200 watts of power delivery. At full load it is audible, but it is not likely an end user will be running this supply at 1000 watt conditions continuously (100%). At 800 watt load, the fan is spinning modestly and will likely be masked by several case fans in a system build.

Temperature (c)
Intake
Exhaust
100W
37
41
250W
38
43
500W
40
50
750W
45
53
1000W
46
54

The large fan works very well in getting rid of heat inside the chassis. Overall results are good.

Maximum load
Efficiency
1090W
89.4

Pushing the PSU above its rated limits generates an efficiency level of around 89.4%. This is not a viable ‘real world’ situation, but it is interesting nonetheless.

The last 12 months have been difficult for a tech enthusiast. Processors, graphics cards and other components have been hard to find in 2021. To make matters worse, in recent months there has been a limited selection of power supplies available via UK etailers and while it is improving a little, the situation is still far from ideal.

A quick search on UK etailer Overclockers UK for 1000W power supplies, shows very little in stock – with only the Corsair HX1000i Platinum Digital supply available at the time of writing for £246.95 (HERE), but it is now out of stock. Corsair have told me that the RM1000x I reviewed today will be available for £169.99, making this 80 Plus Gold rated unit around £76 less expensive than its higher rated brother.

Corsair's RM1000x is a very complete package, load regulation is solid, and it dealt with our cross load test without any difficulty. Efficiency levels are excellent, and ripple suppression is stellar across the board. There are no discernible technical weaknesses with this unit that would cause us any concern.

The fully modular design and low noise levels will ensure the system will suit a wide audience of demanding tech builder – and if the power supply is visible, the neutral black with grey accents will fit perfectly into any themed colour build.

If you can find this unit available for sale today, then we see no reason not to give it a very honest recommendation. It is able to maintain over 1100W sustained load without issue and the 105c Japanese capacitors deliver solid power throughout the range.

Pros:

  • Nicely finished.
  • modular cables.
  • 100% 105C Japanese Capacitors.
  • Meets 80 Plus Gold rated efficiency.
  • quality fan – low noise with high airflow
  • ripple suppression is excellent.
  • 10 year warranty.

Cons:

  • Stock availability could well be an issue in 2021.

KitGuru says: The RM1000X is a quality unit capable of delivering well over the rated 1000 watts. The quiet fan, fully modular design and quality Japanese capacitors ensure long life. And for added peace of mind, Corsair back this with a 10 year warranty.

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