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Corsair AX850 80+ Titanium Power Supply Review

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. We run at 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
• Extech digital sound level meter
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

We test in a single +12V configuration.

DC Output Load Regulation

Combined

DC Load

+3.3V
+5V
+12V
+5VSB
-12V
A
V
A
V
A
V
A
V
A V
85W
0.95
3.34
0.92
5.01
6.00
12.01
0.50
5.03
0.20 -12.01
170W
1.70
3.34
1.67
5.01
12.35
12.00
1.00
5.03
0.20 -12.01
425W
3.00
3.33
3.05
5.01
32.20
12.00
1.50
5.02
0.30 -12.01
640W 4.05 3.33 4.05 5.00 49.00 12.00 2.00 5.02 0.30 -12.01
850W
5.00
3.33
5.23
5.00
65.52
11.98
2.50
5.01
0.50 -12.02

Load regulation is very strong with the rails holding with 1% of recommended specifications.

Corsair AX850 80+ Titanium Power Supply Maximum Load
995W

We managed to get the power supply to deliver 995W before it would shut down, delivering around 145W more than rated specifications.

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
760W 1.0 3.33 1.0 5.01 60.0 11.99 0.2 -12.01 0.50 5.02
165W 15.0 3.32 18.0 4.99 2.0 12.01 0.2 -12.02 0.50 5.01

The power supply dealt with the demanding cross load test very well exhibiting little fluctuation. It was tasked with 60A on the +12V rail and it held at 11.99W. The other rails delivered excellent results also.

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 5 5 5 5
225W 5 5 10 5
450W 5 5 10 5
675W 5 10 15 10
850W 5 10 15 10

Noise suppression is stellar, and top of the class, peaking at 5mV and 10mV from the +3.3V and 5V rails respectively. The +12V rail peaks at 15mV. Great results all round.

Efficiency (%) 240V
100W
91.67
225W
94.83
450W
96.70
675W
95.88
850W 94.72

Efficiency is yet again top of the field, peaking at around 96.5% at close to 50% load. At full load this drops to around 94.52%.

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 Digital Sound Level Noise Decibel Meter Style 2 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
225W
<28.0
450W
<28.0
675W
31.7
850W 33.2

This is one of the quietest power supplies we have tested in the last couple of years. Below 500W the fans didn’t seem to spin at all, and above 500W load then it kicked a little into action. At 600Watts the fan spins up a little, although it would still be classed as ‘whisper quiet’. This highlights the efficiency of the Titanium unit. At 850W, under full load conditions the fan was spinning at around 800 RPM (according to our equipment), and the noise levels were still barely audible.

If you are in the market for an extremely quiet power supply – look no further.

Temperature (c)
Intake
Exhaust
100W
37
38
225W
38
41
450W
39
45
675W
43
48
850W
45
51

The fan may hardly spin at all, but again the efficiency of the Titanium design reaps dividends. The power supply runs cool at all times. Even at full load, the results are incredible.

Maximum load
Efficiency
995 watts
94.2

At 995 watts, this unit managed to deliver efficiency just over 94%. Incredible!

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