Cooler Master GX650 Bronze Power Supply Review

1. Introduction2. Cooler Master GX650 Bronze Power Supply (Bundle)3. Cooler Master GX650 Bronze Power Supply (External)4. Cooler Master GX650 Bronze Power Supply (Internal)5. Testing Methodology and Results6. Closing Thoughts7. View All Pages

Cooler Master have been releasing power supplies now for many years and today we are looking at an upgrade to their long standing 650w non modular unit. It receives 80 Plus Certification and a range of internal design changes, with a new Enhance implementation. Cooler Master are also aiming for competitive pricing to target the mainstream enthusiast audience … but is it worth your money?

The GX650 we are looking at today is the mid range model in a new series of 550w, 650w and 750w power supplies which are hitting the market this week. They are designed for enthusiast systems with a key focus on performance, while maintaining a strong value for money balance. The new design features a dual layer EMI filter and a large quality 120mm PWM controlled fan.

Main feature list:

• Compliance with the latest Intel standard ATX 12V V2.31
• Single +12V Rail provides ample power and strong resistance to any overloading
• High efficiency design that meets 80 Plus Bronze requirements
• Multiple protection designs (OVP/UVP/OPP/OTP/SCP).
• High reliability of over 100,000 hours
• Double Layer EMI Filter reduces Electromagnetic Interference.
• Huge bulk capacitor for hold up times of >17ms when fully loaded
• Efficient transformer that reduces 5Vsb power loss when the system is in off/sleep state.
• EuP ready: To save most power consumption (below 1W in standby mode)
• Five Year Warranty

The Cooler Master GX650 Bronze arrives in a very stylish box, finished with in ‘graffiti art' style.

Inside there is a user manual, warranty information for the five year plan, a power cable for your region and a set of screws for mounting into a chassis. This is not a modular design so the cables are all fitted into the chassis.

The power supply is finished in a very attractive black paint. It does attract fingerprints fairly easily however as it isn't a dull matt finish. The large 120mm fan takes centerstage at the top of the chassis, and strangely enough our review sample didn't have Cooler Master branding on it.

The rear of the PSU is fully vented to help with airflow. To the right is a power connector and a switch for easy access.

The same graffiti style box artwork features on the side of the chassis – this is a sticker, not painted onto the chassis itself.

The GX650 isn't a modular design so the cables all emerge from the front of the unit and are shipped with a thin cable tie around them.

Cable	Amount
MB 20+4 pin	x1 (500mm)
CPU 4+4 pin	x1 (600mm)
PCI E 8 pin (6 pin +2)	x2 (500mm each)
Sata power connectors	x6 (2 cables) (500mm + 100mm each)
Peripheral 4 pin (molex)	x6 (2 cables) (500mm + 100mm each)
Floppy connector	x1

The GX650 has two PCI E 6 pin + 2 connectors, so if your system build needs more (SLI or Crossfire) then you will need to move to the higher end model, the GX750, which is supplied with 4 of these cables.

Cooler Master GX650 Power Supply
DC Output	+3.3V	+5V	+12V	-12V	+5Vsb
Max Output	25A	25A	52A	0.5A	2.5A
Total Power	150w		624W	6W	12.5W
	650W

The GX650 has a single +12V output which is rated to 52A under full load.

Cooler Master are using an ADDA AD1212HS-A71GL fan which is a sleeve bearing design rated to produce 85.2 cfm while emitting a maximum of 39.1 dBa.

Large heatsinks cover the whole width of the internal structure and there are sensors connected to these, which trigger the fan speed changes. This Enhance OEM product is a dual forward design and it offers a double layer EMI filter which gives extra protection from electromagnetic interference.

The design includes a mixture of 105c and 85c rated capacitors, with the two primary CE(M) capacitors are rated 85c, 270uf at 420V.

Cooler Master are using an efficient transformer design which holds power at minimal 5v standby voltage loss so that the system can return quickly when powered on or when resuming from a sleep state. This is a single +12V rail design and all the cables are fully sleeved into the chassis preventing possible long term cable fraying. The PSU offers full multiple protection  – OVP/UVP/OPP/OTP/SCP.

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

We are combining 12V output into a single result.

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
152W	2.05	3.35	2.03	5.05	10.12	12.01	0.50	5.01	0.20	-12.04
270W	3.01	3.32	3.02	5.03	19.07	12.00	0.50	5.00	0.30	-12.03
400W	4.02	3.30	5.02	5.01	29.19	11.98	1.00	4.98	0.30	-12.01
523W	6.01	3.28	7.06	4.98	38.21	11.94	1.50	4.96	0.30	-12.00
652W	8.04	3.26	9.03	4.96	48.35	11.91	2.50	4.95	0.30	-12.00

Output load regulation is solid holding all primary rails within 3% of the nominal voltage.

Cooler Master GX650	Maximum Load
	707.2W

The power supply would shut down at 707.2W, gracefully. We found the protection circuitry to work very 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	3.31	1.0	5.02	48.0	11.83	0.2	-12.04	0.50	5.00
145W	12.0	3.25	15.0	4.97	2.0	12.01	0.2	-12.01	0.50	5.00

The Cooler Master supply held fairly well across the output tests, with only the +12V rail dipping to 11.83V standing out as a minor negative point.

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
152W	5	5	15	5
270W	10	10	25	10
400W	15	10	35	15
523W	20	10	40	15
652W	20	15	45	15

Ripple results all fall within the tolerance guidelines above, with the +12V output hitting a maximum of 45mV under full load. +5V hits 15mV and +3.3V peaks at 20 mV.

Efficiency (%)
152W	83.77
270W	86.12
400W	86.45
523W	84.32
652W	83.45

These results are good for an 80 Plus Bronze rated power supply, peaking at over 86 percent efficiency at around 50 percent load. At full load the efficiency drops to around 83.45 percent.

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)
152W	28.9
270W	29.3
400W	32.7
523W	34.6
652W	35.3

The GX650 is almost silent right up to around 400W load when the fan starts to compensate for rising internal temperatures. At full load it is clearly audible – rating over 35dBa, but we wouldn't assume this would be a realistic long term situation.

Temperature (c)
	Intake	Exhaust
152W	35	38
270W	36	40
400W	39	47
523W	43	52
652W	46	56

The large 120mm helps to ensure that temperatures are held within good parameters. It does spin up in the last 20% of maximum load. Temperatures reach a maximum of +10c above internal intake conditions.

Maximum load	Efficiency
707.2W	82.1

Pushing the PSU above its rated limits generates an ultimate efficiency level of around 82.1%. This is not a viable ‘real world’ situation, but its interesting nonetheless.

Cooler Master set some lofty goals for the new GX650 power supply – offer a cost effective solution for the mass market while delivering solid all round performance. The new updated Enhance design achieves 80 Plus Bronze efficiency ratings in our testing and it held solid over several weeks of ‘real world' testing, including powering a high end system with an overclocked nVidia GTX580 and Intel Core i7 980X processor.

The technical analysis shows that the design is effective. There are some minor fluctuations with Cross Load Testing on the 12V+ output, but it is nothing significant or worrying. Noise suppression is also a strong point, with all rails holding well within the rated parameters. 12V+ peaked at 45 mV which is a good result.

The choice of quality ADDA 120mm fan ensures that the components all receive adequate cooling. Cooler Master have opted for a slightly aggressive fan setting within the upper 15-20% of ultimate power delivery, meaning the PSU remains  audible, although it is never intrusive or annoying.

On an aesthetic level, Cooler Master have aimed for a ‘street graffiti' style box and sticker appearance, clearly to improve the cool factor with the buying public. Its superficial, but the bold yellow and orange ghetto font will stand out in a store. The unit itself is surprisingly understated with plain black paint job and black fan.

We don't have confirmed pricing just yet, but we are assured that it will be very competitively marketed in the UK (around the £55 inc vat mark).

Pros:

• Good all round performance
• looks are appealing
• capable design
• will be competitively priced.
• five year warranty gives peace of mind.

Cons:

• Non modular design means there will always be plenty of cable routing.

KitGuru says: A solid buy for an enthusiast user. Those who have a more demanding graphics card configuration should aim higher up the range.

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