Visiontek 800W Modular Power Supply Review

1. Introduction2. Visiontek 800W Modular Power Supply (Bundle & Cables)3. Visiontek 800W Modular Power Supply (Exterior)4. Visiontek 800W Modular Power Supply (Interior)5. Visiontek 800W Modular (Super 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 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

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	3.38	1.75	5.07	6.66	12.09	0.5	5.02	0.20	-12.07
200W	3.18	3.36	3.41	5.04	13.52	12.02	1.0	5.00	0.30	-12.10
400W	6.13	3.34	7.13	5.02	27.62	11.98	1.5	4.98	0.50	-12.12
600W	9.45	3.32	10.77	5.00	41.33	11.94	2.0	4.96	0.60	-12.15
800W	13.21	3.29	15.05	4.96	55.32	11.91	2.5	4.93	0.80	-12.18

The Visiontek 800W Modular supply delivers good results in the load regulation test across all output. It held within +/-3% of the nominal voltage.

Visiontek 800W Modular	Maximum Load
	867W

We managed to get the PSU to hit 867W before it would shut down. delivering around 67W more than the 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	3.35	1.0	5.06	60.0	11.90	0.2	-12.09	0.50	5.02
165W	15.0	3.28	18.0	4.97	2.0	12.07	0.2	-12.11	0.50	5.00

Cross loading results fall within parameters, with only a slight dip on the +12V output when loaded with 60A. +3.3V and +5V hold voltage well.

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	15	10	15	15
200W	15	15	15	20
400W	20	20	20	20
600W	25	25	35	25
800W	25	30	50	25

Noise suppression isn’t class leading, although it is well within the rated tolerance levels. +12V peaks at 50 mV under full load.

Efficiency (%)
100W	84.12
200W	86.56
400W	87.88
600W	86.87
800W	84.21

The efficiency results are impressive for an 80 Plus Bronze Certified unit, peaking at just under 88% at 50% load. This drops to around 84% at full 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 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)
100W	29.7
200W	30.8
400W	32.9
600W	34.2
800W	36.6

The power supply is relatively quiet right up until around 600W output when the fan becomes audible, although never that intrusive. At full load the maximum noise level we recorded was 36.6dBa. It isn't practical to be loading this power supply to 800W on a regular basis however.

Temperature (c)
	Intake	Exhaust
100W	36	39
200W	36	41
400W	38	44
600W	39	53
800W	41	55

The temperatures rise to 55c when fully loaded, or 14c above the ambient threshold.

Maximum load	Efficiency
867W	83.4%

For those interested, we measured efficiency when stressing the unit to breaking point. Almost 83.5% at 867W.

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