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Corsair RMi Series 1000W Review

Additional technical assistance: Peter McFarland and Jeremy Price.

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. Due to public requests we have changed our temperature settings – previously we rated with ambient temperatures at 25C, we have increased ambient temperatures by 10c (to 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 with the +12V in single rail mode.

DC Output Load Regulation

Combined

DC Load

+3.3V
+5V
+12V
+5VSB
-12V
A
V
A
V
A
V
A
V
A V
100W
1.53
3.36
1.77
5.08
6.66
12.09
0.50
5.04
0.20
-12.04
200W
3.13
3.35
3.50
5.07
13.50
12.06
1.00
5.03
0.20
-12.04
400W
6.42
3.34
7.04
5.06
27.50
12.03
1.50
5.02
0.30
-12.05
600W
9.81
3.33
10.75
5.05
41.70
12.00
2.00
5.02
0.30
-12.06
800W
13.25
3.33
14.55
5.03
56.40
11.97
2.50
5.01
0.50
-12.06
1000W 16.53 3.33 15.66 5.02 71.40 11.92 3.00 4.99 0.60 -12.06

Load regulation is certainly very good.

Corsair RMi Series 1000W
Maximum Load
1105W

We managed to get another 105 watts from the power supply before the protection circuitry kicked in. Great results.

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 3.33 2.0 5.08 72.0 11.89 0.2 -12.04 0.50 5.02
240W 20.0 3.31 24.0 5.03 2.0 12.10 0.2 -12.04 0.50 5.02

The unit passes the cross loading test with both +3.3V and +5V rails holding steady. The +12V rail droops a little when hit with 72A, but it is not a problem.

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 10 5 10 5
200W 10 5 10 5
400W 10 10 10 5
600W 15 10 10 10
800W 15 10 15 10
1000W 15 15 20 10

Ripple suppression is very good. All rails hold well within the industry rated tolerance levels. +3.3V and +5V peak at 15mV. +12V peaks at 20mV at 100% load.

Edit: 6th July 2015: The +12V figure has been appended as we found that if we were using a USB oscilloscope,with the PSU’s Link interface plugged into a USB port on same system (such as a laptop) electrical noise from the laptop was introduced into the final result.

Efficiency (%)
100W
87.23
200W
88.67
300W
90.21
500W
92.13
800W
91.66
1000W 90.79

Overall efficiency results are very strong indeed, peaking at around 92% between a 500 watt and 600 watt load. This drops to almost 91% efficiency at full load.

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
200W
<28.0
400W
<28.0
600W
29.5
800W 32.6
1000W 33.3

A very quiet power supply thanks to high levels of efficiency and the excellent NR135P Fluid Dynamic bearing fan the company are using. Even at full load the fan is not intrusive at all. It is only really in the last 20% of power output that the fan rotates at around 1000-1100 rpm.

Temperature (c)
Intake
Exhaust
100W
35
38
200W
35
44
400W
37
47
650W
43
50
800W
45
54
1000W 47 59

Temperatures are well controlled and the fan never works that hard – it is disabled at lower power demand completely.

Maximum load
Efficiency
1105W
89.68

Pushing the power supply above its rated limits generates an efficiency level of around 89.68%. This is not a viable ‘real world’ situation, but its interesting nonetheless.

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