Cooler Master Silent Pro M 600W Power Supply Review

1. Introduction2. The Cooler Master Silent Pro M 600W3. Inside the Cooler Master Silent Pro M 600W4. Testing Methodology and Results5. Closing Thoughts6. View All Pages

A good power supply is probably the most important part of any system build, and while KitGuru have focused recently on some seriously high end units such as the Corsair AX1200 and the Enermax Revolution 85+ 1020W, not everyone can afford these (or needs them in the first place).

Today we are focusing on a power supply that can be picked up for £70 inc vat in the UK. The Cooler Master Silent Pro M 600 W unit is a modular PSU with a single 12V rail offering 40A. There are four other models in the range, those being 500W, 700W, 850W and 1000W units. The higher end 850W and 1000W are 80 Plus Bronze certified while the one we have on review today has only received the standard 80 Plus approval.

• Up to 40A on a single +12V rail
• Eco-design for energy and money saving by Active PFC.(>0.9)
• Flat modular cables to eliminate clutter and improve chassis airflow
• Two 6+2 pin PCI-e connectors for multiple high-end graphic card set ups
• Japanese-made capacitors
• Energy efficient design that meets 80 Plus requirements
• Intelligent 135mm fan speed control
• Hybrid copper plus aluminum heat sink
• Anti-vibration silicon padding
• Protection: OVP / UVP / OCP / OPP /OTP / SCP / OLP
• High Power Density (150*150*86 mm)
• High reliability (MTBF > 100,000 hrs)
• Compliant with Intel standard Intel ATX12V V2.3 & SSI EPS 12V V2.91
• Five-year warranty

The Cooler Master PSU arrives in a plain box with a picture of the unit itself on the front.

Inside we are greeted with two Silicon Rubber pads which absorb vibrations during operation. There is also a CD included which has a digital manual on it.

Removing these items and a cardboard protection layer we get access to the unit underneath. The cabling is stored on the side, underneath the UK power connector. The PSU is protected underneath a plastic wrap.

One of the sides is completely vented to allow for quick removal of warm air, there is only a power lead connector and button here. Cooler Master have included a nice little badge on the top of the unit which looks very nice.

The unit is dominated by the large 135mm fan on the bottom – the unit is 15cm in length, so there is little room on any corner. It is a rather plain design which won't be winning any design awards, but it is adequate for the price range.

The 600W Cooler Master unit has six connectors on the rear, two of which are gray for the video card cables. The four black connectors are for SATA and peripheral power cables. The main motherboard connector cable and ATX12V/EPS12V cables are the only cables which are not modular and have nylon outer protection.

Cooler Master Silent Pro M 600W Cable support (each cable is a bullet point):

• 1x 20/24 pin motherboard connector.
• 2x ATX12V connectors which can form a EPS12V connector.
• 2x PCIe power cables (8 pin or 6 pin)
• 3x SATA Cables
• 3x SATA Cables
• 3x Molex Connectors
• 2x Molex & floppy disk connectors

As you may have worked out you can't install all the cabling at the same time however it gives users the option to install whatever they need for their specific computer. If you happen to need every cable installed then you need to spend more cash and aim for a higher model in the range. These modular cables are flat in design.

The 135mm fan in the Silent Pro is manufactured by Yong Lin Tech and is model number DFS132512M. This fan is rated to generate a maximum of 82CFM with a noise rating of 37 dBa. We doubt CoolerMaster will be pushing this close to full speed, but it seems to be a good choice as the airflow ratings are high.

The insides are quite neat with only a couple of wires leading to the modular backplate that haven't been kept together. The unit has clearly been designed with a low profile ethic in mind, allowing for the huge ‘fin style' heatsinks to cover the entire surface area, directly under the airflow of the 135mm fan above them.

The transient filtering stage is composed of two Y capacitors and two X capacitors with an X capacitor after the rectifying stage. This is well in excess of the minimum required and we are off to a very good start indeed. The power supply uses a BU1506 rectifying bridge which can handle up to 15A at 85c with the heatsink system Cooler Master are using.

Two low profile capacitors are used in this unit. Cooler Master are using two 270 uf x 420 V capacitors in parallel.

This power supply is using these two electrolytic capacitors to filter the output from the active PFC circuit. We would assume they have opted for two smaller units to help reduce physical space and to suit the low profile design of the power supply. We also noticed five Schottky rectifiers on the secondary stage, three of which are handling the 12V output. The outputs are controlled by an integrated PS223 circuit which supports under voltage, over voltage, over current and over temperature. As the image above shows, secondary capacitors are manufactured by Teapo.

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
75W	1.08	3.37	1.45	5.06	4.90	12.21	0.50	5.06	0.20	-12.13
150W	2.08	3.35	2.98	5.06	10.05	12.15	0.50	5.04	0.30	-12.12
300W	4.29	3.34	6.00	5.05	20.62	12.08	1.00	5.02	0.30	-12.11
450W	6.58	3.32	8.49	5.04	31.82	12.01	1.50	4.98	0.30	-12.10
600W	9.93	3.29	12.21	4.98	41.80	11.95	2.50	4.91	0.30	-12.09

The Cooler Master unit has good regulation across all the outputs and handles our load tests at a very capable level. All of the primary rails stayed with 3% of the nominal voltage.

Cooler Master Silent Pro M 600W	Maximum Load
	674.2W

We managed to get just over 674W 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
590W	1.0	3.35	1.0	5.02	48.0	11.98	0.2	-12.47	0.50	5.08
145W	12.0	3.26	15.0	5.01	2.0	12.15	0.2	-11.92	0.50	5.03

The Cooler Master PSU handled the Cross loading tests very well and we didn't experience any issues at all. All the voltages remained well within specification.

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
75W	5	5	15	10
150W	5	10	20	10
300W	5	10	35	15
450W	10	15	40	15
600W	10	15	55	20

Ripple results are well within the parameters set down in the ATX12V Ver 2.2 standard. While all the results barely registered on our equipment, the +12V line showed 55mv ripple which while still well within margins, is a little higher than we normally report on KitGuru.

Efficiency (%)
75W	85.21
150W	86.17
300W	86.78
450W	84.64
600W	82.02

These efficiency results are very strong for a unit which is rated only as having standard 80 Plus Certification. While we expected to see figures between 80 and 82 percent across the load testing they were noticeably higher between 82 and 87 percent. As the load passed 400W the efficiency dropped back down to 84 percent, falling to 82 percent 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 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)
75W	16.3
150W	17.8
300W	19.7
450W	22.3
600W	24.8

Our noise testing proved to be massively impressive and we were pleasantly surprised to note a maximum of 24.8dBa from the unit under full load. This is without question one of the quietest power supplies we have tested and it fully lives up to the Cooler Master ‘Silent Pro M' name. Cooler Master have configured the 135mm to spin very slowly when compared to its maximum 2,000 rpm setting (37 dbA).

Temperature (c)
	Intake	Exhaust
75W	35	36
150W	35	37
300W	37	40
450W	41	46
600W	44	50

The large fan design inside the Silent Pro M is very efficient and under 50% load the exhaust temperature doesn't rise that much compared to the intake air. Only around 400-450W does the fan spin up more to help compensate for rising ambient temperatures. A very good balance of low noise levels with reasonable air flow.

Maximum load	Efficiency
674.2W	78.9

Pushing the PSU above its rated limits generates an efficiency level of around 79%. This is not a viable ‘real world' situation, but its interesting nonetheless.

While this power supply is not going to impress our readers who have been following our recent reviews of the high end Corsair AX series, it is worth bearing in mind that this unit only costs £70 in the UK and is rated to the generic '80 Plus certification'.

Generally 80 Plus certified power supplies are meant to deliver between 80 and 82% efficiency levels, but we were pleasantly surprised to record efficiency between 84.62 and 86.78%. Obviously at full load it dropped down giving a final result of 82.02 percent, but this is still a great figure for a unit placed in this very modest category.

The use of high quality 135mm fan means that this PSU also remains reasonably cool at all times, and even under full load it is basically silent, living up to its ‘Silent Pro' naming moniker. People who are building a high quality media centre will love this design as it will add no noise to the system build. The fan never spins anywhere near the maximum rating of 37dBA.

For this specific user base this product is actually one of the best we have tested to date, and the fact that the pricing is now so competitive is the icing on the cake. When it was initially released it was selling for just under £100, its now £70.

KitGuru says: If you are in the market for a well priced power supply which is as silent as a sleeping monk then this should be high on your list of ‘shortlist' products.

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