Tuniq Potency 750 W Power Supply Review
By Gabriel Torres on March 26, 2010


Introduction

Hardware Secrets Golden Award

Tuniq Potency 750 W is a 80 Plus Bronze-certified power supply that can be found costing USD 100 (or only USD 70 after a mail-in rebate). The price is good, but what about performance? Let’s see.

Tuniq Potency 750 W power supply
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Figure 1: Tuniq Potency 750 W power supply.

Tuniq Potency 750 W power supply
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Figure 2: Tuniq Potency 750 W power supply.

Tuniq Potency 750 W isn’t a long power supply, being 6 19/64” (160 mm) deep, using a 135 mm fan on its bottom and featuring active PFC, of course.

No modular cabling is provided. All cables have a nylon protection, but only the one used on the main motherboard cable comes from inside the unit. All wires are 18 AWG, which is the minimum recommended gauge, with the main motherboard cable using thicker 16 AWG wires on the +12 V and +3.3 V outputs, which is always nice to see.

 This cables included are the following:

Although the number of cables is satisfactory, here we could clearly see where the manufacturer saved money: we think that the video card power connectors should use individual cables and it would be better if this unit came with a total of at least nine SATA power connectors instead of six.

Tuniq Potency 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 Tuniq Potency 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.

Tuniq Potency 750 W power supply
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Figure 4: Overall look.

Tuniq Potency 750 W power supply
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Figure 5: Overall look.

Tuniq Potency 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.

Tuniq Potency 750 W power supply
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Figure 7: Transient filtering stage (part 1).

Tuniq Potency 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 Tuniq Potency 750 W.

Primary Analysis

On this page we will take an in-depth look at the primary stage of Tuniq Potency 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, supporting up to 15 A at 110° C, so 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.

Tuniq Potency 750 W power supply
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Figure 9: Rectifying bridge.

The active PFC circuit uses two SPW20N60C3 power MOSFET transistors, each one capable of delivering up to 20.7 A at 25° C or 13.1 A at 100° C in continuous mode (note the difference temperature makes) or 62.1 A in pulse mode at 25° 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 achieve a higher efficiency.

Tuniq Potency 750 W power supply
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Figure 10: Active PFC transistors.

The electrolytic capacitor in charge of filtering the output of the active PFC circuit is from CEC, a company from Hong Kong with manufacturing facilities in mainland China, labeled at 85° C.

In the switching section, another two SPW20N60C3 power MOSFET transistors are used, and the specs for them we’ve already published above.

Tuniq Potency 750 W power supply
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Figure 11: Switching transistors.

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

Tuniq Potency 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 six Schottky rectifiers attached on its secondary heatsink, plus a diode for rectifying the +5VSB output.

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 rail is produced using two ESAD83-004 (“E83-004”) Schottky rectifiers, each one capable of delivering up to 30 A (15 A per internal diode at 90° C, 0.55 V maximum voltage drop), giving us a maximum theoretical current of 43 A or 514 W for the +12 V output.

The +5 V rail is produced using two SBR30U30CT Schottky rectifiers, each one capable of delivering up to 30 A (15 A per internal diode at 140° C, 0.54 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 rail is produced using another two SBR30U30CT Schottky rectifiers, giving us a maximum theoretical current of 43 A or 141 W for this output.

Of course our math is only an exercise, as the real maximum current will depend on the other components used.

Tuniq Potency 750 W power supply
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Figure 13: +12 V, +5 V and +3.3 V rectifiers.

This power supply uses a PS224 monitoring integrated circuit, which features the following protections: over voltage (OVP), under voltage (UVP) and over current (OVP). The over current protection circuit present inside this integrated circuit features four channels. The protection circuit also features an LM393 (dual voltage comparator) integrated circuit.

Tuniq Potency 750 W power supply
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Figure 14: Monitoring circuit.

Electrolytic capacitors from the secondary are mostly from CEC, with some from Teapo and a few solid capacitors on the monitoring circuit printed circuit board.

Power Distribution

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

Tuniq Potency 750 W power supply
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Figure 15: Power supply label.

As you can see, the label lists four +12 V rails. Inside the power supply the unit really has four rails, as we could clearly see four shunts (current sensors), plus the monitoring circuit implements four over current protection channels, which is key to have separated rails (click here to learn more about this subject).

The rails are distributed like this:

This distribution is good because it separates the CPU (EPS12V/ATX12V) from the video cards, however the way the peripheral and SATA power cables were connected is a little bit unusual; most manufacturers would have attached them all on the same rail as the main motherboard cable.

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 tests +12VA input was connected to the power supply +12V1 and +12V3 rails while the +12VB input was connected to the power supply +12V4 rail.

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

149.8 W

295.6 W

453.9 W

603.9 W

753.8 W

% Max Load

20.0%

39.4%

60.5%

80.5%

100.5%

Room Temp.

45.6° C

45.9° C

46.8° C

47.3° C

47.1° C

PSU Temp.

49.6° C

50.4° C

51.1° C

52.6° C

52.0° C

Voltage Stability

Pass

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

Failed on -12 V

AC Power

187.6 W

349.9 W

538.2 W

724.0 W

924.0 W

Efficiency

79.9%

84.5%

84.3%

83.4%

81.6%

AC Voltage

113.6 V

111.6 V

110.6 V

109.0 V

105.8 V

Power Factor

0.980

0.991

0.994

0.995

0.996

Final Result

Pass

Pass

Pass

Pass

Pass

Tuniq Potency 750 W was able to deliver its labeled power at high temperatures.

Efficiency was high when we pulled between 40% and 80% from the unit’s labeled wattage (between 300 W and 600 W), but at light load (20% load, i.e., 150 W) and full load (750 W) efficiency was below the 82% promised by the 80 Plus Bronze certification. This happens because Ecos Consulting, the company in charge of 80 Plus, tests units at 23° C, a temperature that is too low in our opinion, and the higher temperature, the lower efficiency is. Click here for more information on this subject.

Voltage stability was one of the highlights from Tuniq Potency 750 W, with all voltages inside 3% of their nominal values, i.e., voltages were closer to their nominal value than needed, as ATX12V 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.

Noise and ripple were relatively low all the time, except -12 V during test five, which surpassed the 120 mV limit by staying at 137.6 mV. Below you can see the results for test number five. As we always point out, the limits are 120 mV for +12 V and 50 mV for +5 V and +3.3 V and all numbers are peak-to-peak figures.

Tuniq Potency 750 W power supply
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Figure 16: +12VA input from load tester at 753.8 W (60.6 mV).

Tuniq Potency 750 W power supply
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Figure 17: +12VB input from load tester at 753.8 W (60.4 mV).

Tuniq Potency 750 W power supply
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Figure 18: +5V rail with power supply delivering 753.8 W (26.6 mV).

Tuniq Potency 750 W power supply
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Figure 19: +3.3 V rail with power supply delivering 753.8 W (23.0 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 with it still working within ATX12V specs. If we tried to pull more than that, the power supply would shut down, showing that one its protections are working well.

Input

Overload Test

+12V1

33 A (396 W)

+12V2

33 A (396 W)

+5V

18 A (90 W)

+3.3 V

18 A (59.4 W)

+5VSB

3 A (15 W)

-12 V

0.5 A (6 W)

Total

937.4 W

% Max Load

125.0%

Room Temp.

42.4° C

PSU Temp.

48.6° C

AC Power

1,197 W

Efficiency

78.3%

AC Voltage

103.3 V

Power Factor

0.997

Main Specifications

Tuniq Potency 750 W power supply specs include:

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

Conclusions

Tuniq Potency 750 W comes to compete with other cost-effective 750 W power supplies like Seventeam ST-750P-AF and SilverStone Element ST75EF. This model from Tuniq offers as big advantage costing less than its main competitors: USD 100 against USD 110 (Seventeam ST-750P-AF) or USD 130 (SilverStone Element ST75EF). After a mail-in rebate offered at Newegg.com it will cost you only USD 70, which is an unbelievable price for a 750 W power supply that can really deliver its labeled power at high temperatures (in fact we could pull up to 937 W from it).

Seventeam ST-750P-AF and SilverStone Element ST75EF offer an efficiency that is little bit higher. In fact, if we were the ones behind the 80 Plus certification we wouldn’t give it the Bronze seal, since at high temperatures this unit can’t deliver a minimum of 82% efficiency at light (20%, i.e., 150 W) and full (750 W) loads. Interesting enough the manufacturer knows that, since it publishes efficiency as “Up to 80%” (unless this is a translation error from Chinese to English).

On the other hand, this unit presents an outstanding voltage regulation (3% tolerance instead of the standard 5%) and low noise and ripple levels, being better than its competitors on these two aspects.

For its price, Tuniq Potency 750 W is an excellent unit. Of course there are better 750 W power supplies on the market, but they will cost you way more.

Originally at http://www.hardwaresecrets.com/article/Tuniq-Potency-750-W-Power-Supply-Review/955


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