Cooler Master GX 450 Power Supply Review

1. Introduction2. Cooler Master GX 450 (Bundle)3. Cooler Master GX 450 (Exterior)4. Cooler Master GX 450 (Interior)5. Testing Methodology and Results6. Closing Thoughts7. View All Pages

If you are in the market for a power supply for your new media center, then today we might just have the perfect partner for review. Cooler Master have just released their GX 450 power supply which features a strong 12V rail, double layer EMI filter and an intelligent 120mm controllable fan.

We have looked at several Cooler Master power supplies in the past, and the quality has always been high. The new GX 450 will offer more than enough power for a performance system aimed at media and HD television gaming.

Specifications:

• 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 requirements (85% typical)
• Multiple protection designs (OVP/UVP/OPP/OTP/SCP)
• High reliability (MTBF>100,000 hours)
• Double Layer EMI filter reduces Electronmagnetic 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 an off/sleep state
• EuP ready: To save most power consumption (below 0.5W in standby mode)
• Five year warranty

The GX 450 arrives in a funky, graffiti style purple and black box which is sure to garner attention in a store.

The bundle is fairly spartan, a power cable, some literature, 4 mounting screws and a 5 year warranty card.

This PSU is not a modular design so all the cables are tied up and fed directly into the chassis.

The unit is finished in a plan dark finish with the name of the product on the side in the same graffiti typeface as the box. There is a single large 120mm fan at the top.

DC Output Rating
Voltage	+3.3V	+5V	+12V	-12V	+5Vsb
Current (A)	24A	15A	35A	0.3A	2.5A
Ripple (mV)	50	50	120	120	50
Total Power	120W		420W	3.6W	12.5W
	450W

Considering the modest power output, the GX450 can deliver a high level of current to the single 12V rail.

Cable	Amount	Length
MB 20+4 pin	x1	500mm
CPU 4+4 pin	x1	600mm
PCI e 6 pin x 1	x1	500mm
Sata power connectors	x3	500mm + 600mm + 700mm
Sata power connectors	x2	500mm + 600mm
Peripheral 4 pin (molex)	x3	500mm + 600mm + 700 mm
Floppy connector	x1	800mm

There is only one PCIe 6 pin power connector which means if you want to use higher end graphics cards then power adapters will need to be used.

Cooler Master have chosen the ADDA AD1212MS-A71GL, a 120x120x25mm sleeve bearing fan which is oil impregnated and operates between 10.8 to 13.2 V. Start up voltage is 7.0V DC nominal. It requires 4.08 watts and rotates up to 2,050 rpm generating a maximum of 80.5 CFM. Noise ratings show a maximum of 38.0 DbA.

On the upper heatsink there are two black heatshrink sleeves over the fins, these are used for fan control and overtemperature protection thermistors. This is a dual forward design offering up to 85% efficiency.

The PCB is a clean design and the capacitor is rated to 105c, 330 uF, 420V.  It can produce a hold up time of 17ms when fully loaded.

The cabling is fully sleeved into the chassis and is well protected against possible long term fraying.

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
	A	V	A	V	A	V	A	V
75W	1.05	3.34	1.47	5.07	4.84	12.13	0.50	5.05
150W	2.41	3.32	3.17	5.05	9.70	12.19	1.00	5.05
250W	3.69	3.31	5.18	5.02	16.50	12.05	1.50	5.02
350W	4.97	3.27	7.06	4.98	23.52	12.02	2.00	5.00
450W	6.73	3.23	9.15	4.96	31.24	11.93	2.50	4.95

Load regulation seems fine, and falls within specifications.

Cooler Master GX 450	Maximum Load
	473.4

We managed to push the supply to 473.4 watts before it would shut down safely.

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
385.4W	2.0	3.28	2.0	5.03	30.0	11.98	0.2	-11.98	0.50	5.02
170.5W	18.0	3.21	12.0	4.88	4.0	12.08	0.2	-11.75	0.50	4.95

Our first test placed a heavy load (30a) on the +12 V output with a light load on the remaining voltages. The GX 450 held fairly well, remaining well within specification. It also passed the second test within recommended specifications.

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	25	15	30	10
150W	30	20	30	15
250W	35	25	35	20
350W	40	25	45	25
450W	45	30	50	25

Ripple results were all within ATX12V specification, although the +3.3V showed 45 mV under full load, still within specification, but close to the edge.

Efficiency (%)
75W	83.45
150W	84.23
250W	84.78
350W	83.13
450W	81.44

For an 80 Plus unit, the efficiency figures are pretty good across the full range of our testing.

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	27.8
150W	28.6
250W	29.4
350W	32.7
450W	36.8

The 120mm fan is reasonably quiet until the unit is pushed to 80%+ of the rated output level, then it can be heard, at full load it is clearly audible generating almost 37 dBa of noise.

Temperature (c)
	Intake	Exhaust
75W	35	38
150W	36	39
250W	38	47
350W	40	50
450W	43	55

The 120mm fan helps to maintain reasonable ambient temperatures inside the chassis, rising to a maximum of 55c under full load.

Maximum load	Efficiency
473.4W	79.3

Pushing the PSU above its rated limits generates an efficiency level of around 79.3%. This is not a viable ‘real world’ situation, but its interesting nonetheless.

The Cooler Master GX450 is a decent power supply, aimed at the budget market. A good option for enthusiast users wanting to build an entry level gaming system or performance oriented media center.

Efficiency ratings for an 80 Plus unit are solid, delivering a maximum efficiency rating of around 85% mid way through the output range. This drops to around 81% under full load. The 120mm fan does a reasonable job of maintaining fairly good temperatures, although it does seem to be working quite hard above 80% of the rated output, and is clearly audible. We realistically expect that in a high definition media system environment this PSU will be taxed with less than 50% of its given output.

Ripple results fall within the rated tolerance guidelines, although we found that the +3.3V result was just inside the 50mV guideline figure. Load regulation is quite strong, never dropping into what we would consider a dangerous zone.

While none of the technical testing will make the product stand out in a crowded marketplace, Cooler Master will be focusing on the lowest possible pricepoint to reach the widest audience. We don't have confirmed pricing yet as the product is not released, however the GX 550 was retailing for around £55 inc vat, therefore we would expect the GX450 to be a very low cost choice for a consumer on a budget.

KitGuru says: A good budget offering from CoolerMaster, but they will have to fight hard for it to be seen in such a crowded marketplace.

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