Seasonic Snow Silent 1050W PSU Review (XP3)

1. Introduction2. Seasonic Snow Silent 1050W (Bundle/Cables)3. Seasonic Snow Silent 1050W (External)4. Seasonic Snow Silent 1050W (Internal)5. Seasonic Snow Silent 1050W (High Res Gallery)6. Testing Methodology & Results7. Closing Thoughts8. 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 – 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 the power supply with the fan in the ‘normal’ state.

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
100W	1.54	3.34	1.76	5.07	6.65	12.12	0.50	5.01	0.20	-12.03
200W	3.13	3.34	3.50	5.07	13.50	12.12	1.00	5.01	0.20	-12.03
400W	6.40	3.34	7.05	5.07	27.50	12.12	1.50	5.00	0.30	-12.04
600W	9.82	3.33	10.75	5.05	41.70	12.10	2.00	5.00	0.30	-12.03
800W	13.27	3.33	14.56	5.05	56.40	12.08	2.50	4.99	0.50	-12.04
1050W	16.55	3.33	15.75	5.05	74.00	12.08	3.00	4.99	0.60	-12.03

Load regulation is fantastic with all the rails holding tight, within 1.5%.

Seasonic Snow Silent 1050W PSU	Maximum Load
	1205W

We managed to get another 155W from the power supply before the protection circuitry kicked in. The supply was undamaged and it was ready to fire up again when we dropped the load to a more realistic level.

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	5.03	72.0	12.08	0.2	-12.02	0.50	5.01
240W	20.0	3.33	24.0	5.03	2.0	12.09	0.2	-12.03	0.50	5.01

The Seasonic Snow Silent 1050W power supply delivered a great set of results in the demanding Cross load test, as shown above.

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	10	15	5
200W	15	10	15	10
400W	15	10	20	10
600W	15	15	20	15
800W	15	15	25	15
1050W	15	20	30	15

Ripple suppression is very good. All of the rails exhibit very low ripple and the +12v rail for instance peaks at 30mV, well within the rated specifications.

Efficiency (%)
100W	85.7
200W	88.6
300W	93.3
500W	94.5
800W	93.3
1050W	92.3

The overall efficiency results are excellent, peaking at 94.5% at 500W. This drops close to 92% efficiency at full load, a very impressive result.

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	28.8
600W	30.5
800W	32.4
1050W	33.7

The 120mm fan in the Snow Silent 1050W performs exceptionally well, hitting 33.7dBa under full load. Most of the time the power supply is barely audible. It is only after 800watts is demanded that the fan can be heard – not a realistic situation for many running this system. We would recommend a 1250W rated power supply if you need a constant 800-1000watt demand.

Temperature (c)
	Intake	Exhaust
100W	35	37
200W	35	40
400W	37	42
650W	43	52
800W	45	54
1050W	47	60

Temperatures are well controlled thanks to the efficiency of the unit. The fan spins slow most of the time, only spinning up in the last 20% of load.

Maximum load	Efficiency
1205W	91.4

Pushing the power supply above its rated limits generates an efficiency level of around 91.4%. This is not a viable ‘real world’ situation, but its interesting nonetheless.

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