OCZ Fatal1ty 750 W Power Supply Review
By Gabriel Torres on June 8, 2010


Introduction

Hardware Secrets Golden Award

After buying PC Power & Cooling, OCZ decided to keep selling power supplies without modular cabling system and with a single +12 V rail under that brand, and sell under their own brand only products with modular cabling system. Fatal1ty 750 W is, therefore, a unit with this feature.

Because of this new direction, OCZ discontinued their Fatal1ty 700 W unit, which didn’t have a modular cabling system and had a single +12 V rail. Even thought they share the same name both units are completely different internally.

The Fatal1ty 750 W is manufactured by Highpower.

OCZ Fatal1ty 750 W Power Supply
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Figure 1: OCZ Fatal1ty 750 W power supply.

OCZ Fatal1ty 750 W Power Supply
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Figure 2: OCZ Fatal1ty 750 W power supply.

OCZ Fatal1ty 750 W is 6 19/64” (160 mm) deep, using a 135 mm fan on its bottom and featuring active PFC, of course.

The reviewed power supply has a modular cabling system with eight connectors (four red ones for video cards and four black ones for SATA/peripheral cables) and it comes with three cables permanently attached to the unit. The cables included are the following:

All wires are 18 AWG, except the +12 V (yellow) and +3.3 V (orange) wires on the main motherboard cable and the ATX12V/EPS12V connector, which are 16 AWG, i.e., thicker, which is very nice to see.

The number of cables for video cards – four – is perfect for a 750 W product, plus each connector is installed on an individual cable. All cables used on the modular cabling system are flat, which is a plus. The cables, however, are a little bit short for a product on this power range, we’d like this unit better if it had wires at least 20” (51 cm) long. Six SATA connectors seem enough but honestly it would be better if this unit had one extra SATA connector on each cable for a total of eight SATA connectors.

OCZ Fatal1ty 750 W Power Supply
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Figure 3: Cables.

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

A Look Inside The OCZ Fatal1ty 750 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, and then in the following pages we will discuss in detail the quality and ratings of the components used.

OCZ Fatal1ty 750 W Power Supply
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Figure 4: Overall look.

OCZ Fatal1ty 750 W Power Supply
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Figure 5: Overall look.

OCZ Fatal1ty 750 W Power Supply
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Figure 6: Overall look.

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. 

On this power supply this stage is flawless. It has one X capacitor and two Y capacitors more than the minimum required, plus one X capacitor after each rectifying bridge.

OCZ Fatal1ty 750 W Power Supply
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Figure 7: Transient filtering stage (part 1).

OCZ Fatal1ty 750 W Power Supply
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Figure 8: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion about the components used in the OCZ Fatal1ty 750 W.

Primary Analysis

On this page we will take an in-depth look at the primary stage of OCZ Fatal1ty 750 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one TS15P05G rectifying bridge in its primary, supports up to 15 A at 110° C, if a heatsink is used. This component is installed on the same heatsink as the active PFC transistors. In theory you would be able to pull up to 1,725 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 1,380 W without burning itself out. Of course, we are only talking about these components, and the real limit will depend on all the other components in this power supply.

OCZ Fatal1ty 750 W Power Supply
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Figure 9: Rectifying bridge.

The active PFC circuit uses two FCA20N60 power MOSFET transistors, each one capable of delivering up to 20 A at 25° C or 12.5 A at 100° C in continuous mode (note the difference temperature makes) or 60 A in pulse mode at 25° C. These transistors present a 150 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 achieve a higher efficiency.

OCZ Fatal1ty 750 W Power Supply
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Figure 10: Active PFC transistors.

The electrolytic capacitor used to filter the output of the active PFC circuit is Japanese from Chemi-Con and labeled at 105° C. This is the best possible configuration.

In the switching section, another two FCA20N60 power MOSFET transistors are used. The specifications for these transistors were already published above.

OCZ Fatal1ty 750 W Power Supply
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Figure 11: Switching transistors.

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

OCZ Fatal1ty 750 W Power Supply
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Figure 12: Active PFC/PWM combo controller.

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

Secondary Analysis

This power supply comes with eight Schottky rectifiers attached to its secondary heatsink.

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 produced by three MBR4045PT Schottky rectifiers, each one capable of delivering up to 40 A (20 A per internal diode at 125° C, 0.80 V maximum voltage drop). This gives us a maximum theoretical current of 86 A or 1,029 W for the +12 V output.

The +5 V output is produced by two PFR30L45CT Schottky rectifiers, each one capable of delivering up to 30 A (15 A per internal diode at 125° C, 0.52 V maximum voltage drop). This gives us a maximum theoretical current of 43 A or 214 W for the +5 V output.

The +3.3 V output is produced by another two PFR30L45CT, giving us a maximum theoretical current of 43 A or 141 W for the +3.3 V output.

The eighth rectifier, an SR1045, is used by the +5VSB output.

OCZ Fatal1ty 750 W Power Supply
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Figure 13: Rectifiers.

This power supply uses a PS224 monitoring integrated circuit, which over voltage protection (OVP), under voltage protection (UVP) and four OCP (over current protection) channels, one for +3.3 V, one for +5 V, and two for +12 V. Additionally the monitoring circuit uses an LM393 integrated circuit (a dual voltage comparator) to expand the number of channels of the over current protection circuit.

OCZ Fatal1ty 750 W Power Supply
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Figure 14: Monitoring circuit.

Electrolytic capacitors from the secondary are also Japanese, from Chemi-Con and labeled at 105° C.

Power Distribution

In Figure 15, you can see the power supply label containing all the power specs.

OCZ Fatal1ty 750 W Power Supply
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Figure 15: Power supply label.

According to the label this unit has four +12 V rails. Inside the power supply the unit has four “shunts” (current sensors – see Figure 16) and although the monitoring integrated circuit supports only two +12 V OCP channels, it uses two voltage comparators to “expand” these inputs. So this unit really has over current protection enabled and, therefore, four +12 V rails.

OCZ Fatal1ty 750 W Power Supply
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Figure 16: Four “shunts” (current sensors).

The four rails are distributed like this:

We think this is not a good distribution, especially because the rails are not easily identified outside the unit. Therefore, you may end up having your CPU and your video card running on the same rail, and even two video cards and the CPU running on the same rail.

Now let’s see if this power supply can really deliver 750 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 how the reviewed unit behaved 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. On 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 review +12VA input was connected to the power supply +12V1 and +12V3 rails while the +12VB input was connected to the power supply +12V2 and +12V3 rails.

Input

Test 1

Test 2

Test 3

Test 4

Test 5

+12VA

5 A (60 W)

11 A (132 W)

16 A (192 W)

22 A (264 W)

27 A (324 W)

+12VB

5 A (60 W)

10 A (120 W)

16 A (192 W)

21 A (252 W)

27 A (324 W)

+5V

2 A (10 W)

4 A (20 W)

6 A (30 W)

8 A (40 W)

10 A (50 W)

+3.3 V

2 A (6.6 W)

4 A (13.2 W)

6 A (19.8 W)

8 A (26.4 W)

10 A (33 W)

+5VSB

1 A (5 W)

1 A (5 W)

1.5 A (7.5 W)

2 A (10 W)

2.5 A (12.5 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

149.3 W

300.4 W

450.2 W

598.3 W

748.8 W

% Max Load

19.9%

40.1%

60.0%

79.8%

99.8%

Room Temp.

45.1° C

45.7° C

48.2° C

44.2° C

48.8° C

PSU Temp.

44.3° C

44.7° C

45.8° C

44.5° C

47.6° C

Voltage Stability

Pass

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

Pass

AC Power

177.9 W

352.1 W

532.6 W

720.0 W

918.0 W

Efficiency

83.9%

85.3%

84.5%

83.1%

81.6%

AC Voltage

112.1 V

109.4 V

106.2 V

104.0 V

103.3 V

Power Factor

0.947

0.979

0.989

0.993

0.995

Final Result

Pass

Pass

Pass

Pass

Pass

OCZ Fatal1ty 750 W can really deliver its labeled power at high temperatures.

Efficiency was very good, being above 83% at all tests except when we pulled 750 W from the unit, when it dropped to 81.6%. Being an 80 Plus Bronze unit it should deliver 82% efficiency at full load, but if you follow our power supply reviews know that several times what is promised by 80 Plus isn’t achieved because they test power supplies at a room temperature of only 23° C and we test power supplies at a room temperature of at least 45° C (efficiency drops with temperature).

Voltage regulation was superb, with all voltages inside 3% of their nominal values(i.e., voltages were closer to their nominal value than needed, as ATX spec allows voltages to be up to 5% from their nominal values, 10% for -12 V). This includes the -12 V output, which usually doesn’t like to stay within a tolerance this tight.

And finally we have noise and ripple, which were low all the time. Below you can see the results for test number five. As we always point out, the limits are 120 mV for +12 V and -12 V outputs and 50 mV for +5 V, +3.3 V and +5VSB outputs, and all numbers are peak-to-peak figures.

OCZ Fatal1ty 750 W Power Supply
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Figure 17: +12VA input from load tester at 748.8 W (58.6 mV).

OCZ Fatal1ty 750 W Power Supply
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Figure 18: +12VB input from load tester at 748.8 W (50.0 mV).

OCZ Fatal1ty 750 W Power Supply
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Figure 19: +5V rail with power supply delivering 748.8 W (12.0 mV).

OCZ Fatal1ty 750 W Power Supply
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Figure 20: +3.3 V rail with power supply delivering 748.8 W (13.4 mV).

Now let’s see if we could pull more than 750 W from this unit.

Overload Tests

Below you can see the maximum we could pull from this power supply. If we tried to pull more than that the power supply would shut down. However, after a few seconds the unit burned under this load (around 980 W).

Input

Overload Test

+12V1

33 A (396 W)

+12V2

33 A (396 W)

+5V

20 A (100 W)

+3.3 V

20 A (66 W)

+5VSB

3 A (15 W)

-12 V

0.5 A (6 W)

Main Specifications

OCZ Fatal1ty 750 W power supply specs include:

* Researched at Google Shopping on the day we published this review.

Conclusions

OCZ Fatal1ty 750 W is a nice option if you want to buy a decent 750 W power supply with modular cabling system at an affordable price. It competes directly with 750 W models from Seventeam like ST-750ZAF (with modular cabling system) and ST-750PAF (without modular cabling system) and it has as advantages lower ripple/noise level, higher efficiency and better voltage regulation. In summary, OCZ Fatal1ty 750 W is probably the power supply on this power range with the best cost/benefit ratio on the market today.

If you want to save even more, research carefully before buying it, because at this moment prices are varying quite a bit, from USD 105 to USD 129. If you are able to buy it for USD 105 you will be doing an outstanding deal, but even at USD 129 is not a bad buy at all.

Originally at http://www.hardwaresecrets.com/article/OCZ-Fatal1ty-750-W-Power-Supply-Review/1019


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