OCZ ZT 650W Power Supply Review

1. Introduction2. OCZ ZT 650W Power Supply (Bundle & Cabling)3. OCZ ZT 650W Power Supply (External)4. OCZ ZT 650W Power Supply (Internal)5. OCZ ZT 650W Power Supply (Super High Res Gallery)6. Testing Methodology and Results7. Closing Thoughts8. View All Pages

Those old enough will remember OCZ as being one of the leaders in the enthusiast memory sector and in recent years they have focused on the Solid State Drive sector, producing many cutting edge products. They took over PC Power & Cooling a few years ago to enhance their company portfolio and have been releasing a solid array of supplies for both the mass market and enthusiast sector. Today we are looking at the latest 650W from the ZT power Supply series which rests right in the middle of their range, between the ModXStream Pro and Fatal1ty Series.

The ZT 650W is a 80 Plus Bronze Certified design, and completely modular to help create a neat and tidy system build. The range includes a large PWM 140mm fan to ensure high airflow, while lowering noise emissions. It has a single +12V rail with 54A available.

Technical Overview:

• Available in 550W, 650W, 750W
• Single +12V rail for efficient power distribution
• Heavy-duty protection circuitry
• Fully Modular Cabling System
• 80-Plus Bronze Certified (85% efficient at typical load)
• 140mm ball-bearing fan
• Dimensions: 150 x 86 x 175mm (W x L x H)
• Rated at 45°C ambient
• Premium 105°C electrolytic capacitors
• Erp compliant, low power usage in standby mode
• Active PFC
• ATX 12V 2.2 Compliant
• MTBF: 100,000 hours
• 5-year warranty

The ZT 650W ships in a primarily black box with bright yellow accenting, with large text focusing on the modular design.

Inside the power supply is on the left, with the cabling and other accessories in a separate box on the right.

OCZ supply a user manual with an overview of the ZT series, along with cable ties and screws to mount the power supply into a computer case. There is also a region specific power cable, which is pictured below.

The 650W supply contains the following modular cables:

• 1 x 20+4-pin ATX
• 1 x 4+4-pin ESP/12V CPU
• 2 x 6+2-pin PCI-E
• 6 x 4-pin Peripheral
• 9 x 5-pin SATA
• 1 x Floppy

To protect the surface during shipping, the power supply is protected inside a soft cloth bag which is pulled securely tight.

OCZ have kept the appearance simple and dark, which is the most compatible appearance for the majority of system builds. The product name and specifications are highlighted in yellow. The large 140mm fan takes centerstage at the top of the unit, with ‘Z' branding in the middle. The power supply measures 86x150x175mm.

The front of the power supply has all the modular cabling connectors, all clearly labelled to ensure an easy build. This is a 100% modular design so even the standard ATX power cable isn't wired.

The rear is vented to aid with airflow. There is a power connector and switch offset to the side.

OCZ ZT 650W Power Supply
DC Output	+5V	+3.3V	+12V	-12V	+5Vsb
Max Output	30A	24A	54A	.5A	3A
Combined	170W		648W	6W	15W
Total	650W

The power supply has a single 12V+ rail capable of delivering 54A of power.

The power supply uses a Yate Loon D14BH-12 fan which can generate up to 140cfm of airflow at around 48.5 dBa (2,800 rpm). This fan should be controlled to spin much slower than this however and we will test the noise emissions later in the review.

This is a Great Wall design, the same company who produce the ZX series for OCZ. There are several rows of black heatsinks separating components.

OCZ are using Teapo capacitors, rated 560μF, 420V, 105°C. Transient filtering starts at the AC receptacle with one X and two Y capacitors. We noticed that they aren't using a Metal Oxide Varistor which could be seen as a bad point of the design.

Capacitors on the secondary side are by Rubycon and Nippon Chemi Con. This design has extra ripple filtering in place with Teapo and Chemi Con capacitors on the modular PCB section.

On this page we present some super high resolution images of the product taken with the 24.5MP Nikon D3X camera and 24-70mm ED lens. These will take much longer to open due to the dimensions, especially on slower connections. If you use these pictures on another site or publication, please credit Kitguru.net as the owner/source. You can right click and ‘save as’ to your computer to view later.

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

We are combining 12V output into a single result.

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
152W	2.07	3.40	2.04	5.02	10.11	12.18	0.50	5.01	0.20	-12.05
270W	3.03	3.38	3.06	5.01	19.11	12.12	0.50	5.00	0.30	-12.01
400W	4.01	3.30	5.04	4.97	29.17	12.08	1.00	4.98	0.30	-12.00
523W	6.04	3.27	7.04	4.93	38.16	12.00	1.50	4.96	0.30	-11.97
652W	8.07	3.24	9.01	4.87	48.18	11.88	2.50	4.95	0.30	-11.94

Output load regulation is solid holding all primary rails within 2.5% of the nominal voltage.

OCZ ZT 650W	Maximum Load
	724.1W

The power supply would shut down at 724.1W, gracefully. We found the protection circuitry to work very well.

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
590W	1.0	3.34	1.0	5.00	48.0	11.85	0.2	-12.05	0.50	5.02
145W	12.0	3.23	15.0	4.95	2.0	12.08	0.2	-12.03	0.50	5.01

The supply held well across the output tests, with the +12V rail dipping to 11.85V when loaded with 48A quickly.

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
152W	5	5	10	5
270W	5	10	15	10
400W	10	10	15	15
523W	10	15	25	20
652W	10	20	35	25

Ripple results all fall within the tolerance guidelines above, and they are impressive all round. The 12V+ output peaks at 35mV under full load.

Efficiency (%)
152W	85.42
270W	87.33
400W	88.45
523W	86.49
652W	85.65

These results are very strong for an 80 Plus Bronze rated power supply, peaking at over 88 percent efficiency at around 50 percent load. At full load the efficiency drops to 85.65 percent.

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)
152W	29.9
270W	30.3
400W	33.5
523W	34.3
652W	36.5

The ZT 650W is relatively quiet under around 400W load when the fan spins up a little, becoming audible. When we get into the last 20% of ultimate power delivery it is spinning quite fast and is clearly audible. It wouldn't be classed as annoying, but for better acoustics performance, we would prefer to keep the power supply around the 500W output range (or lower) under load. This is more practical anyway because if you need 600W of constant power output you should be aiming higher in the OCZ range.

Temperature (c)
	Intake	Exhaust
152W	35	37
270W	36	38
400W	39	43
523W	43	49
652W	46	53

The large 140mm has no problem maintaining good internal ambient temperatures. Going on these results we feel OCZ could have relaxed the fan profile a little to lower the noise emissions.

Maximum load	Efficiency
724.1W	83.3

Pushing the PSU above its rated limits generates an ultimate efficiency level of around 83.3%. This is not a viable ‘real world’ situation, but its interesting nonetheless.

The OCZ ZT 650W is up against some very tough competition in this price sensitive sector, but it is a proficient design which is both technically capable and attractive. Being a fully modular design means that you never have to deal with the routing of surplus cables, a major selling point against other non modular designs in the same price zone.

Technically we have no concerns with this design, the unit delivers some exceptional efficiency results for an 80 Plus Bronze certified power supply and load regulation is impressive. It also dealt well with our cross loading tests, remaining stable under all conditions.

The ZT 650W passes our noise suppression tests with flying colours, achieving a maximum 35mV figure on the 12V+ output at full load, well within industry tolerance guidelines. The power supply managed to hold a 724W maximum load for a short time, before shutting down gracefully.

The 140mm Yate Loon fan is a good performer, although we feel that OCZ have opted for a slightly aggressive fan profile at the expense of a little noise. We wouldn't say it was emitting intrusive levels of noise, but for a media center environment there are quieter alternatives.

UK pricing is said to be around the £79.99 inc vat point, which means this power supply offers good value for money. With the 5 year warranty there is also plenty of peace of mind, long term.

Pros:

• Excellent efficiency.
• Pure modular.
• Technically a very solid unit.
• 5 year warranty.
• Stable load delivery.

Cons:

• Slightly noisy under high loud.

Kitguru says: An excellent mid range power supply for an enthusiast gaming system.

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