Home / Tech News / Featured Tech Reviews / Be Quiet! Straight Power E9 580W Power Supply Review

Be Quiet! Straight Power E9 580W 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 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
110W
3.03
3.35
3.04
5.07
6.51
12.15
1.50
5.04
220W
6.21
3.32
6.23
5.04
13.50
12.07
1.50
5.03
340W
9.31
3.30
9.23
5.03
21.11
12.02
1.50
5.03
445W
12.45
3.28
12.41
5.01
27.53
11.97
1.50
5.02
580W
15.70
3.26
14.64
4.98
38.21
11.91
1.50
5.00

Voltage regulation holds well, with only minor fluctuation from the +12V output.

Be Quiet! Straight Power E9 580W Maximum Load
673.5

The power supply managed to output just over 673 watts before shutting 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
493W 1.0 3.33 1.0 5.05 40.0 11.86 0.2 -11.98 0.50 5.02
153W 15.0 3.28 15.0 4.99 2.0 12.11 0.2 -12.09 0.50 5.00

Cross loading shows minor +12V fluctuation, dropping from 12.11 to 11.86 when hit with 40 amps. Not a major issue by any means, but recordable with the equipment.

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
110W 5 10 15 10
220W 10 10 20 15
340W 10 15 30 20
445W 10 15 40 20
580W 15 15 45 20

Noise suppression is held well within rated parameters, peaking at 45 mV on the +12V output. +3.3V, +5V both peak at 15 mV at full load.

Efficiency (%)
110W
86.64
220W
89.57
340W
91.78
445W
89.56
580W
88.45

Efficiency is high, peaking at almost 92 percent at 50 percent load.

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)
110W
28.0
220W
28.0
340W
28.0
445W
28.0
580W 30.5

This is one of the quietest power supplies we have ever tested, barely measuring on our test equipment, even at full load. Incredible results.

Temperature (c)
Intake
Exhaust
110W
36
39
220W
38
42
340W
39
48
445W
42
51
580W
44
55

The active fan helps maintain good temperature variables, rising to a 11c above ambient intake at full load.

Maximum load
Efficiency
673.5W
86.7

Pushing the PSU above its rated limits generates an efficiency level of around 86.7%. This is not a viable ‘real world’ situation, but its interesting nonetheless.

Become a Patron!

Check Also

PNY All-in-One USB-C Dock Review

Could this be the dock for you if your laptop has limited connectivity options?