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Seasonic Platinum 1000W Modular Power Supply Review

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

DC Output Load Regulation

Combined

DC Load

+3.3V
+5V
+12V
+5VSB
-12V
A
V
A
V
A
V
A
V
A V
100W
1.55
3.33
1.78
5.05
6.69
12.06
0.50
5.04
0.20
-12.03
250W
3.42
3.33
4.45
5.05
17.16
12.05
1.00
5.04
0.30
-12.03
500W
7.07
3.33
9.15
5.04
34.67
12.05
2.00
5.03
0.50
-12.04
750W
11.06
3.33
13.74
5.04
52.75
12.03
2.50
5.03
0.60
-12.05
1000W
16.86
3.32
18.96
5.03
71.94
12.01
3.00
5.03
0.80
-12.07

The load regulation of this power supply is probably the best we have seen. Period. The +3.3V output hardly moved at all, even under full load. Fantastic, class leading results.

Seasonic Platinum 1000W Maximum Load
1197W

We managed to get another 197W from the power supply before the protection circuitry kicked in. The supply was undamaged and it was ready to fire up again when we were a little more sensible with the load.

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 5.05 72.0 12.00 0.2 -12.03 0.50 5.03
240W 20.0 3.31 24.0 5.03 2.0 12.06 0.2 -12.02 0.50 5.02

The Seasonic power supply absolutely blitzed these intensive stress tests, hardly fluctuating at all.

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 20 15
250W 15 10 20 15
500W 20 15 35 20
750W 25 20 45 25
1000W 25 20 50 25

These aren't the best noise suppression results we have seen, however the results are all still well within rated parameters. +12V output peaks at 50 mV which is good, although slightly worse than some competing products we have reviewed in recent months.

Efficiency (%)
100W
86.7
250W
92.9
500W
93.7
750W
92.2
1000W
91.8

The efficiency results are excellent, peaking at just under 94% at 500W. This drops to 91.8 % efficiency at full load, still 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 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)
100W
28.0
250W
28.0
500W
29.7
750W
31.4
1000W 33.1

The Seasonic Platinum 1000W is basically silent up to around 550W. After this, the fan becomes active, causing a little noise increase. At 1000W it is clearly audible, although surprisingly quiet. A fantastic set of results.

Temperature (c)
Intake
Exhaust
100W
35
39
250W
35
42
500W
38
47
750W
43
53
1000W
46
57

The fan is only really active above 500W and the temperature results are fantastic especially when considering the amazingly low noise levels.

Maximum load
Efficiency
1197W
90.4

Pushing the PSU above its rated limits generates an efficiency level of around 90.4%. This is not a viable ‘real world’ situation, but its interesting nonetheless.

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