Introduction

OCZ has just released a new incarnation of their mainstream StealthXStream series, with models ranging from 400 W to 700 W. Today we are going to review the 600 W version and see how it differs from the original StealthXStream 600 W.

Like the original StealthXStream 600 W, the new StealthXStream 2 600 W is manufactured by FSP.

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Figure 1: StealthXStream 2 600 W power supply

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Figure 2: StealthXStream 2 600 W power supply

The StealthXStream 2 600 W is 5.5” (140 mm) deep, using a 120 mm ball-bearing fan manufactured by Yate Loon Electronics (model D12BH-12) on its bottom.

This unit features active PFC, of course.

The new StealthXStream 2 600 W doesn’t come with a modular cabling system. All cables have nylon sleeves, which come from inside the power supply. The cables included are the following:

• Main motherboard cable with a 20/24-pin connector, 18.1” (46 cm) long
• One cable with two ATX12V connectors that together form an EPS12V connector, 18.1” (46 cm) long
• One cable with one six/eight-pin connector and one six-pin connector for video cards, 17.3” (44 cm) to the first connector, 3.2” (8 cm) between connectors
• One cable with three SATA power connectors, 18.1” (46 cm) to the first connector, 8.7” (22 cm) between connectors
• One cable with three standard peripheral power connectors, 18.1” (46 cm) to the first connector, 7.9” (20 cm) between connectors
• One cable with two standard peripheral power connectors and one floppy disk drive power connector, 18.1” (46 cm) to the first connector, 7.9” (20 cm) between connectors

All wires are 18 AWG.

The cable configuration shows that this is a low-end product. The two video card connectors are installed on the same cable, instead of using separate cables, and there are only three SATA power connectors. Even though the distance between the SATA connectors is above the average (usually manufacturers use a distance of 5.9”/15 cm between connectors), you may find it hard to install your SATA optical drive and your SATA hard disk drive on the same cable. We think this product deserved at least two SATA cables with at least two SATA connectors each (three would be great).

This is almost the same configuration used by the original StealthXStream 600 W. The only difference between the two models is that the older model uses two six-pin connectors for video cards, instead of having one six/eight-pin connector and one six-pin connector.

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Figure 3: Cables

Now let’s take an in-depth look inside this power supply.

A Look Inside The StealthXStream 2 600 W

We decided to disassemble this power supply to see what it looks like inside, how it is designed, and what components are used. Please read our Anatomy of Switching Power Supplies tutorial to understand how a power supply works and to compare this power supply to others.

This page will be an overview, while in the following pages we will discuss the quality and ratings of the components used in detail. The printed circuit board of the StealthXStream 2 600 W seems to be identical to the one used by the original StealthXStream 600 W. The only difference we could see was the “name” of the design: the original StealthXStream 600 W is based on a printed circuit board labeled “FSP700-80GLC (NEW) REV: 1” (part number 3BS0110312GP), while the new StealthXStream 600 W is based on a printed circuit board labeled “FSP850-80GLN (REV1)” (part  number 3BS0224611GP). In the following pages we will see whether the components are the same or not.

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Figure 4: Top view

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Figure 5: Rear quarter view

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Figure 6: Front quarter view

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Figure 7: Printed circuit board

Transient Filtering Stage

As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality is its filtering stage. The recommended components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor), and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components, usually removing the MOV and the first coil. 

This power supply has all required components but the MOV, which is in charge of removing spikes coming from the power grid. On the other hand, it has two Y capacitors and two X capacitors more than the minimum required.

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Figure 8: Transient filtering stage (part 1)

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Figure 9: Transient filtering stage (part 2)

In the next page we will have a more detailed discussion of the components used in the StealthXStream 2 600 W.

Primary Analysis

On this page we will take an in-depth look at the primary stage of the OCZ StealthXStream 2 600 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU606 rectifying bridges connected in parallel, both attached to the same heatsink used by the switching transistors. Each bridge supports up to 6 A at 100º C so, in theory, you would be able to pull up to 1,380 W from a 115 V power grid. Assuming 80% efficiency, the bridges would allow this unit to deliver up to 1,104 W without burning themselves. Of course, we are only talking about these components, and the real limit will depend on all the other components in this power supply. These are the same components used on the original StealthXStream 600 W.

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Figure 10: Rectifying bridges

The active PFC circuit uses two SPA20N60C3 MOSFETs, each one capable of delivering up to 20.7 A at 25º C or up to 13.1 A at 100º C in continuous mode (note the difference temperature makes), or up to 62.1 A in pulse mode at 25º C. These transistors present a 190 mΩ resistance when turned on, a characteristic called RDS(on). The lower this number the better, meaning that the transistors will waste less power and the power supply will have a higher efficiency.

Here we could see a difference between the original StealthXStream 600 W and the new StealthXStream 2 600 W. Even though the model of the transistors is he same, the older model has three transistors in its active PFC circuit, while the new model carries two. The StealthXStream 2 600 W has a space where the third transistor was installed.

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Figure 11: Active PFC transistors and diode

The electrolytic capacitor used to filter the output of the active PFC circuit is from OST and labeled at 105º C.

In the switching section, another two SPA20N60C3 MOSFET transistors are used. The specifications for these transistors are already published above. The original StealthXStream 600 W use transistors that are a little bit "weaker" here (18 A at 25º C, 12.1 A at 100º C, 265 mΩ resistance).

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Figure 12: Switching transistors

The primary is controlled by the omnipresent CM6800 active PFC/PWM combo circuit.

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Figure 13: Active PFC/PWM combo controller

Now let’s take a look at the secondary of this power supply.

Secondary Analysis

This power supply has eight MBR3045CT Schottky rectifiers (30 A maximum current, 15 A per internal diode at 100º C, 0.84 V maximum voltage drop), all attached to the secondary heatsink. This is an improvement over the old StealthXStream 600 W, which used weaker rectifiers (MBR2045CT, 20 A maximum current) for the +12 V output. So the new StealthXStream 2 600 W has a higher maximum theoretical current on its +12 V output. It is important to note, however, that other power supplies based on the same design, like the Zalman ZM600-HP and OCZ GameXStream 700 W, use eight of the MBT3045CT's.

The maximum theoretical current each line can deliver is given by the formula I / (1 - D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode. Just as an exercise, we can assume a typical duty cycle of 30%.

The +12 V output is generated using four of the available rectifiers , giving us a maximum theoretical current of 86 A or 1,029 W for the +12 V output.

The +5 V output is generated using two of the available rectifiers, giving us a maximum theoretical current of 43 A or 214 W.

The +3.3 V output is generated using the other two available rectifiers, giving us a maximum theoretical current of 43 A or 141 W.

Of course these are all theoretical figures. The real current limits will depend on other components, especially on the coil used.

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Figure 14: The +3.3 V, +5 V and +12 V rectifiers

The outputs are monitored by a PS223 integrated circuit. This circuit supports over voltage (OVP), under voltage (UVP), over temperature (OTP), and over current (OCP) protections. This circuit offers four over current protection channels (one for +3.3 V, one for +5 V, and two for +12 V). A WT7518D integrated circuit expands the number of +12 V over current protection channels to four, correctly matching the number of +12 V rails announced by the manufacturer.

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Figure 15: Monitoring circuit

The electrolytic capacitors available in the secondary are from Teapo and labeled at 105º C.

Power Distribution

In Figure 16, you can see the power supply label containing all the power specs.

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Figure 16: Power supply label

This power supply has four +12 V rails, and we confirmed this by analyzing its circuit. The manufacturer did a great job of describing the components that are connected to each rail on the power supply label, but there is one error: the label talks about a “PCI-E2” connector, that doesn’t exist (both video card connectors of this power supply are attached to the same cable). The four available rails are divided like this:

• +12V1 (yellow wire with blue stripe): ATX12V connector labeled as “CPU1”
• +12V2 (yellow wire with white stripe): ATX12V connector labeled as “CPU2”
• +12V3 (solid yellow wire): Main motherboard cable and all peripheral connectors
• +12V4 (yellow wire with black stripe): Video card auxiliary power connectors

Now let’s see if this power supply can really deliver 600 W.

Load Tests

We conducted several tests with this power supply, as described in the article, Hardware Secrets Power Supply Test Methodology.  

First we tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching the behavior of the reviewed unit under each load. In the table below, we list the load patterns we used and the results for each load.

If you add all the power listed for each test, you may find a different value than what is posted under “Total” below. Since each output can vary slightly (e.g., the +5 V output working at 5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. In the “Total” row, we are using the real amount of power being delivered, as measured by our load tester.

The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During our tests, the +12VA input was connected to the power supply +12V3 and +12V4 rails, while the +12VB input was connected to the power supply +12V1 and +12V2 rails.

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12VA	4 A (48 W)	9 A (108 W)	13 A (156 W)	17.5 A (210 W)	22.5 A (270 W)
+12VB	4 A (48 W)	9 A (108 W)	13 A (156 W)	17.5 A (210 W)	22 A (264 W)
+5V	1 A (5 W)	2 A (10 W)	4 A (20 W)	6 A (30 W)	8 A (40 W)
+3.3 V	1 A (3.3 W)	2 A (6.6 W)	4 A (13.2 W)	6 A (19.8 W)	8 A (26.4)
+5VSB	1 A (5 W)	1 A (5 W)	1.5 A (7.5 W)	2 A (10 W)	3 A (15 W)
-12 V	0.5 A (6 W)	0.5 A (6 W)	0.5 A (6 W)	0.5 A (6 W)	0.5 A (6 W)
Total	114.9 W	240.8 W	353.7 W	477.8 W	602.4 W
% Max Load	19.2%	40.1%	59.0%	79.6%	100.4%
Room Temp.	45.2º C	44.8º C	45.0º C	46.6º C	45.4º C
PSU Temp.	49.2º C	48.8º C	49.1º C	50.0º C	51.3º C
Voltage Regulation	Pass	Pass	Pass	Pass	Pass
Ripple and Noise	Pass	Pass	Pass	Pass	Pass
AC Power	134.7 W	277.2 W	411.0 W	565.1 W	735.0 W
Efficiency	85.3%	86.9%	86.1%	84.6%	82.0%
AC Voltage	111.7 V	113.2 V	110.6 V	108.5 V	107.4 V
Power Factor	0.974	0.985	0.991	0.994	0.995
Final Result	Pass	Pass	Pass	Pass	Pass

The StealthXStream 2 600 W can really deliver its labeled wattage at high temperatures.

We were really impressed by the new StealthXStream 2 600 W. During our tests it achieved efficiency compatible with the 80 Plus Bronze certification, even though this power supply officially has only the 80 Plus standard certification. Efficiency peaked at 87% with the power supply delivering 40% of its rated capacity (240 W).

Voltage regulation was another highlight of the product. During our tests all outputs were within 3% of their nominal values (including the -12 V output), meaning that they were closer to their nominal values than required (the ATX12V specification allows a tolerance of 5% for the positive voltages and 10% for the negative voltages).

Noise and ripple levels were always low. Below you can see the results for the power supply outputs during test number five. The maximum allowed is 120 mV for +12 V and -12 V and 50 mV for +5 V and +3.3 V. All values are peak-to-peak figures.

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Figure 17: +12VA input from load tester during test five at 602.4 W (34.4 mV)

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Figure 18: +12VB input from load tester during test five at 602.4 W (33.4 mV)

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Figure 19: +5V rail during test five at 602.4 W (12.2 mV)

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Figure 20: +3.3 V rail during test five at 602.4 W (18.2 mV)

Let’s see if we can pull even more from the StealthXStream 2 600 W.

Overload Tests

Below you can see the maximum we could pull from this power supply. If we tried to pull more the power supply would shut down, showing that a protection kicked in, which is great.

Input	Overload Test
+12VA	26 A (312 W)
+12VB	26 A (312 W)
+5V	10 A (50 W)
+3.3 V	10 A (33 W)
+5VSB	3 A (15 W)
-12 V	0.5 A (6 W)
Total	712.5 W
% Max Load	118.8%
Room Temp.	48.4º C
PSU Temp.	51.2º C
AC Power	888 W
Efficiency	81.0%
AC Voltage	105.7 V
Power Factor	0.996

Main Specifications

The specs of the StealthXStream 2 600 W include:

• Standards: ATX12V 2.2
• Nominal labeled power: 600 W
• Measured maximum power: 712.5 W at 48.4º C ambient
• Labeled efficiency: 83% at typical load (i.e., 50% load or 300 W) at 115 V, 80 Plus Standard certification
• Measured efficiency: Between 82.0% and 86.9% at 115 V (nominal, see complete results for actual voltage)
• Active PFC: Yes
• Modular Cabling System: No
• Motherboard Power Connectors: One 20/24-pin connector and two ATX12V connectors that together form an EPS12V connector
• Video Card Power Connectors: One cable with one six/eight-pin connector and one six-pin connector
• SATA Power Connectors: Three on one cable
• Peripheral Power Connectors: Five on two cables
• Floppy Disk Drive Power Connectors: One
• Protections: Over voltage (OVP), over current (OCP) and short-circuit (SCP) protections – although not listed by the manufacturer, this unit has under voltage protection (UVP)
• Warranty: Three years
• Real Manufacturer: FSP
• More Information: http://www.ocztechnology.com
• Average price in the US*: USD 80.00

* Researched at Newegg.com on the day we published this review.

Conclusions

The new StealthXStream 2 600 W really surprised us. It achieved up to 87% efficiency, with numbers that would easily qualify it for the 80 Plus Bronze certification, even though it carries only the standard 80 Plus. Voltages were always very close to their nominal values (3% regulation), and noise and ripple levels were very low at all times.

We could pull up to 712 W from this power supply with efficiency still above 80%. So you buy a 600 W power supply and get a 700 W.

Compared to the original StealthXStream 600 W, the new model uses stronger +12 V rectifiers and switching transistors, two active PFC transistors instead of three, and one of the video card power connectors was upgraded to a six/eight-pin model.

On the down side, we think it could have more SATA connectors.

Costing only USD 80 (or USD 60 after a mail-in rebate), it is a very good option for the user looking for a good entry-level power supply.