OCZ StealthXStream 2 600 W Power Supply Review

1. Introduction2. The OCZ StealthXStream 2 600W (External)3. The OCZ StealthXStream 2 600W (Internal)4. Testing Methodology and Results5. Closing Thoughts6. 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. Over the coming months this configuration is likely to be adjusted further and fine tuned. Ambient room temperatures are kept to a ‘real world’ realistic condition of 25c with air conditioning.

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 are running all four 12V rails into one final test result (12v)

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
115W	1	3.32	1	5.01	8	12.10	1	5.01	0.5	-12.19
355W	4	3.30	4	5.00	26	12.02	1.5	4.95	0.5	-12.02
480W	6	3.27	6	4.97	35	11.95	2	4.91	0.5	-11.86
601W	8	3.19	8	4.91	44.5	11.79	3	4.88	0.5	-11.78

OCZ 600W	Maximum Load
	719.5W

The PSU remained stable, even at full load and the results fall within safe parameters and guidelines. At a sustained 600W the unit was rock solid for many hours. We then cranked our testing equipment to see how far we could push it, the PSU turned off at around 720W which was around 20% over its rated maximum figures. Anything higher and it would shut down immediately. The Overcircuit protection system worked well which is good to see.

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 this unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load	+3.3V	+5V	+12V	5VSB
115W	10	10	20	15
355W	15	10	25	20
480W	15	15	30	25
601W	20	20	35	25

The ripple results fall well within a ‘pass' rating and these are very good, particularly for a product in such a competitive price bracket.

Efficiency (%)
115W	86.2
355W	87.1
480W	85.4
601W	83.3

These efficency ratings are very close to the figures that OCZ quoted and they are actually within the 80 Plus Bronze certification. OCZ have modestly classed this unit as a 80 Plus Standard certified unit – however we saw peaks of 87 percent at around 280-350W.

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 Corsair 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)
115W	27.5
355W	28.9
480W	33.1
601W	38.3

These low levels are very good and only when the unit is loaded to 450W or higher does it become that noticeable. This was obviously in our silent testing environment, under real world conditions with a few case fans you will not hear the PSU until around 75%+ load.

Exhaust Temperature (c)
115W	27
355W	32
480W	37
601W	44

Exhaust temperatures are once again very good indeed and again it only really starts to get warm when at 75% load or higher. When we hit 90-100% load the air coming out of the back of the PSU was relatively warm. Again this isn't a viable real world condition, if you need 600W of constant power, aim higher up the wattage chain.

Maximum load	Efficiency
719.5W	80.3%

Out of interest we lastly decided to measure unit efficency at our maximum rated figure of 719.5W and were pleasantly surprised to see figures of just over 80%. This is not a real world situation incidentally, you would not be running a 600W power supply at 720W long term.

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