Cooler Master Silent Pro Gold 1200W Power Supply Review

1. Introduction2. Cooler Master Silent Pro Gold 1200W (External)3. Cooler Master Silent Pro Gold 1200W (Internal)4. Testing Methodology and Results5. Closing Thoughts6. View All Pages

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 recently – 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

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
330W	5.50	3.35	5.50	5.04	21.25	12.10	0.87	5.02	0.20	-12.15
620W	11.00	3.33	11.00	5.04	42.50	12.08	1.75	5.01	0.40	-12.17
918W	16.50	3.31	16.50	5.03	63.75	12.04	2.62	4.99	0.60	-12.18
1204W	22.00	3.29	22.00	4.99	85.00	12.01	3.5	4.97	0.80	-12.20

The Cooler Master PSU maintains good voltage regulation across all the outputs and handles the load tests well. Primary rails all remained within 2 percent of nominal voltage.

Cooler Master Silent Pro Gold 1200W	Maximum Load
	1321W

We managed to coak just over 1320W out of the PSU before it would shut down, gracefully. We are happy to report that the overcircuit protection works well.

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
1190W	1.0	3.35	1.0	5.05	62.0	12.05	0.05	-12.15	0.05	5.01
195W	22.0	3.28	22.0	4.96	1.0	11.97	0.05	-11.97	0.05	4.97

A very good set of results under cross loading, only minor fluctuation, more noticeable on the -12V rail.

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 Cooler Master unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load	+3.3V	+5V	+12V	5VSB
330W	10	15	20	15
620W	20	15	30	20
918W	25	25	60	25
1204W	30	35	85	30

Ripple results are higher than we normally record in our power supply reviews, with the 12V output maxing at around 85mv. This is not worrying however as it is still well within specifications (120mv). We wouldn't class this unit as having fantastic ripple suppression, but they are all well within specifications. Bear in mind that at 900W the 12v recorded around 60mv, within the lower half of the recommended tolerance levels.

Efficiency (%)
330W	88.9
620W	91.8
918W	90.4
1204W	88.5

Efficiency is good throughout the range, peaking at around 92% at 600W.

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 Corsair Power Supply we have taken it into our acoustics room environment and have set our Digital Sound Level Noise Decibel Meter Style 2 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 Refridgerator
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)
330W	26.4
620W	27.8
918W	30.5
1204W	35.8

A fantastic set of results, with the unit only audible at the higher end of the power scale. Under most real world conditions, it registers below 30 dBa.

Temperature (c)
	Intake	Exhaust
330W	35	37
620W	35	37
918W	38	42
1204W	43	53

The fan is optimised for a low noise balance, but due to the efficiency of the unit, the temperatures are only 10c over ambient at full load, which is a very impressive set of results.

Maximum load	Efficiency
1321W	86.7%

At 1321W the Cooler Master Gold PSU rated at 86.7 percent efficiency. This is not a viable ‘real world’ situation, but its interesting nonetheless.

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