BeQuiet! Straight Power E9 700W PSU Review

1. Introduction2. BeQuiet Straight Power E9 700W (Bundle & Cables)3. BeQuiet Straight Power E9 700W (External)4. BeQuiet Straight Power E9 700W (Internal)5. BeQuiet Straight Power E9 700W (Super High Res Gallery)6. Testing Methodology and 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 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
• Extech digital sound level meter
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

12V output is combined for our testing

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
174W	3.26	3.32	3.25	5.05	11.54	12.10	0.76	5.09	0.12	-12.04
352W	7.53	3.29	7.55	5.03	23.07	12.05	1.52	5.04	0.25	-12.08
525W	11.25	3.26	11.29	5.00	34.51	11.98	2.26	5.02	0.37	-12.11
700W	15.04	3.21	15.05	4.92	46.61	11.94	3.0	4.96	0.50	-12.13

The BeQuiet Straight Power E9 700W delivers decent regulation although there is a marked droop on +3.3V from 3.32 to 3.21 under full load. +5V dropped from 5.05 to 4.92 under full load.

BeQuiet Straight Power E9 700W	Maximum Load
	791W

We managed to squeeze 791W from the PSU 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.

Combined DC Load	+3.3V		+5V		+12V		-12V		+5VSB
	A	V	A	V	A	V	A	V	A	V
590W	1.0	3.32	1.0	5.02	48.0	11.82	0.2	-12.03	0.5	5.03
190W	18.2	3.19	20.1	4.79	2.0	12.08	0.2	-11.96	0.5	4.98

The BeQuiet Straight Power unit didn't deliver the best results in our Crossloading test, dropping on the +5V output from 5.02 to 4.79. + 12V dropped to 11.82.

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
174W	10	10	25	10
352W	10	10	35	15
525W	15	20	45	20
700W	15	25	60	20

Ripple results are decent although at full load the +12V output measures around 60mV. Not a problem result however and well within tolerance specifications (120mV), although it is a little higher than many others we have reviewed in recent months.

Efficiency (%)
174W	89.22
352W	91.96
525W	91.12
700W	88.94

The efficiency figures are excellent, achieving around 92 percent efficiency at 50 percent load. This drops to just under 89% efficiency at full load. Great results.

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 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)
174W	<28.0
352W	<28.0
525W	<28.0
700W	30.9

This is an exceptionally quiet power supply, not registering on our equipment, until around 640W load is demanded. Even at full load it is barely audible. A testament to the excellent SilentWings fan incorporated into the unit.

Temperature (c)
	Intake	Exhaust
174W	36	39
352W	38	43
525W	40	49
700W	43	53

The large Silentwings fan helps to keep temperatures well in check, rising to a 10c above ambient figure at full load.

Maximum load	Efficiency
791W	87.6%

We measured the efficiency beyond the rated limits of the supply and recorded 87.6% at 791W. Its not a real world everyday rating, but interesting regardless.

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