Cougar RS 650 W Power Supply Review
By Gabriel Torres on June 27, 2011


Introduction

Cougar is a brand that belongs to HEC/Compucase, originally targeted to the European market. Recently, they started expanding to the North American market as well. The RS series is comprised of models from 300 W to 650 W. Let’s see how the 650 W model fared in our tests.

Cougar RS 650 W power supply
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Figure 1: Cougar RS 650 W power supply

Cougar RS 650 W power supply
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Figure 2: Cougar RS 650 W power supply

The Cougar RS 650 W is 5.5” (140 mm) deep, using a 120 mm sleeve bearing fan on its bottom (Young Lin Tech DFS122512M).

This unit doesn’t have a modular cabling system, and only the main motherboard cable is protected with a nylon sleeve. This power supply comes with the following cables:

All wires are 18 AWG, which is the correct gauge to be used.

The cable configuration is compatible with an entry-level product, as it only has two video card power connectors, installed on the same cable. The number of SATA power connectors and their distribution across three cables is excellent for a mainstream power supply.

Cougar RS 650 W power supply
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Figure 3: Cables

Let’s now take an in-depth look inside this power supply.

A Look Inside the Cougar RS 650 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.

On this page we will have an overall look, and then in the following pages we will discuss in detail the quality and ratings of the components used.

Cougar RS 650 W power supply
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Figure 4: Top view

Cougar RS 650 W power supply
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Figure 5: Front quarter view

Cougar RS 650 W power supply
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Figure 6: Rear quarter view

Cougar RS 650 W power supply
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Figure 7: The 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. 

In this power supply, this stage is flawless. It has two X capacitors and four Y capacitors more than the minimum required.

Cougar RS 650 W power supply
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Figure 8: Transient filtering stage (part 1)

Cougar RS 650 W power supply
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Figure 9: Transient filtering stage (part 2)

In the next page we will have a more detailed discussion about the components used in the Cougar RS 650 W.

Primary Analysis

On this page we will take an in-depth look at the primary stage of the Cougar RS 650 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one KBU10J rectifying bridge, attached to an individual heatsink. This component supports up to 10 A at 75° C, so in theory, you would be able to pull up to 1,150 W from a 115 V power grid. Assuming 80% efficiency, the bridge would allow this unit to deliver up to 920 W without burning itself out. Of course, we are only talking about this particular component. The real limit will depend on all the components combined in this power supply.

Cougar RS 650 W power supply
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Figure 10: Rectifying bridge

The active PFC circuit uses two MDP18N50 MOSFETs, each supporting up to 18 A at 25° C or 11 A at 100° C in continuous mode (note the difference temperature makes), or 72 A at 25° C in pulse mode. These transistors present a 270 mΩ resistance when turned on, a characteristic called RDS(on). The lower the number the better, meaning that the transistor will waste less power, and the power supply will have a higher efficiency.

Cougar RS 650 W power supply
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Figure 11: Active PFC transistors and diode

The electrolytic capacitor that filters the output of the active PFC circuit is Japanese, from Chemi-Con, and labeled at 85° C.

In the switching section, another two MDP18N50 MOSFETs are used in the traditional two-transistor forward configuration. The specifications for these transistors were already discussed above.

Cougar RS 650 W power supply
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Figure 12: One of the switching transistors

The primary is controlled by an FAN4800 active PFC/PWM combo controller.

Cougar RS 650 W power supply
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Figure 13: Active PFC/PWM combo controller

Let’s now take a look at the secondary of this power supply.

Secondary Analysis

The Cougar RS 650 W has five Schottky rectifiers attached to the 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. As an exercise, we can assume a duty cycle of 30 percent.

The +12 V output uses two SBL30L30CT Schottky rectifiers (30 A, 15 A per internal diode at 140° C, 0.57 V maximum voltage drop), giving us a maximum theoretical current of 43 A or 514 W for this output.

The +5 V output uses one STPS30L45CT Schottky rectifier (30 A, 15 A per internal diode at 135° C, 0.74 V maximum voltage drop), giving us a maximum theoretical current of 21 A or 107 W for this output.

The +3.3 V output uses two SBR40U60CT Schottky rectifiers (40 A, 20 A per internal diode at 100° C, 0.60 V maximum voltage drop), giving us a maximum theoretical current of 57 A or 189 W for this output.

Cougar RS 650 W power supply
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Figure 14: The +3.3 V, +5 V, and +12 V rectifiers

This power supply uses a PS223 monitoring integrated circuit, which supports over voltage (OVP), under voltage (UVP), over current (OCP), and over temperature (OTP) protections. This chip has four OCP channels, one for +3.3 V, one for +5 V, and two for +12 V, correctly matching the number of +12 V rails advertised by the power supply manufacturer (two).

Cougar RS 650 W power supply
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Figure 15: Monitoring circuit

The electrolytic capacitors available in the secondary are from Teapo and Su’scon, and are labeled at 105° C.

Power Distribution

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

Cougar RS 650 W power supply
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Figure 16: Power supply label

This power supply is sold as having two +12 V rails, which is correct, since this unit has two +12 V over current protection circuits (see previous page). Click here to understand more about this subject.

The two +12 V rails are distributed as follows:

This is the typical configuration of power supplies with two +12 V rails. It is adequate, as it puts the CPU (ATX12V/EPS12V connectors) and the video card in separate rails.

How much power can this unit really deliver? Let’s find out.

Load Tests

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

Usually we test power supplies with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity. However, this power supply exploded when we pulled 650 W from it. Because of that, we asked the manufacturer to send us a second sample, since we couldn’t discard the possibility of having received a defective sample. With the new sample, we increased power from 80% to 100% in 5% increments, to see the exact amount of power we could pull from this unit without it burning (if it happened again).

If you add all the powers listed for each test, you may find a different value than what is posted under “Total” below. Since each output can have a slight variation (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 this test, the +12VA input was connected to the power supply +12V1 rail, while the +12VB input was connected to the power supply +12V2 rail.

Input

Test 1

Test 2

Test 3

Test 4

+12VA

5 A (60 W)

10 A (120 W)

15 A (180 W)

20 A (240 W)

+12VB

5 A (60 W)

10 A (120 W)

15 A (180 W)

20 A (240 W)

+5 V

1 A (5 W)

2 A (10 W)

4 A (20 W)

6 A (30 W)

+3.3 V

1 A (3.3 W)

2 A (6.6 W)

4 A (13.2 W)

6 A (19.8 W)

+5VSB

1 A (5 W)

1 A (5 W)

1.5 A (7.5 W)

2 A (10 W)

-12 V

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

Total

141.9 W

271.3 W

410.6 W

546.8 W

% Max Load

21.8%

41.7%

63.2%

84.1%

Room Temp.

46.2° C

46.0° C

46.6° C

48.8° C

PSU Temp.

48.0° C

47.9° C

48.5° C

50.3° C

Voltage Regulation

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

AC Power

167.6 W

318.4 W

489.6 W

674.0 W

Efficiency

84.7%

85.2%

83.9%

81.1%

AC Voltage

115.1 V

113.1 V

110.7 V

108.3 V

Power Factor

0.951

0.955

0.976

0.985

Final Result

Pass

Pass

Pass

Pass


Input

Test 5

Test 6

Test 7

+12VA

21 A (252 W)

22 A (264 W)

23 A (276 W)

+12VB

21 A (252 W)

22 A (264 W)

23 A (276 W)

+5 V

6.5 A (32.5 W)

7 A (35 W)

7.5 A (37.5 W)

+3.3 V

6.5 A (21.45 W)

7 A (23.1 W)

7.5 A (24.75 W)

+5VSB

2 A (10 W)

2 A (10 W)

2 A (10 W)

-12 V

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

Total

575.7 W

602.7 W

Failed

% Max Load

88.6%

92.7%

Failed

Room Temp.

48.5° C

45.4° C

Failed

PSU Temp.

49.0° C

51.7° C

Failed

Voltage Regulation

Pass

Pass

Failed

Ripple and Noise

Pass

Pass

Failed

AC Power

712.0 W

754.0 W

Failed

Efficiency

80.9%

79.9%

Failed

AC Voltage

108.2 V

108.2 V

Failed

Power Factor

0.986

0.987

Failed

Final Result

Pass

Pass

Failed

Unfortunately, the Cougar RS 650 W can’t deliver its labeled power at high temperatures. The maximum we could pull from it was 600 W. Above that, the unit explodes. As explained, we tested two samples, with the same results. In the next page you will find more detail of the explosion, including the video we made.

Efficiency was high when we pulled between 20% and 60% of the labeled wattage (i.e., between 130 W and 390 W), ranging from 83.9 to 85.2 percent. At 80% load (520 W), efficiency dropped to 81.1%, still a good number for a power supply with the standard 80 Plus certification. However, you can see that we got 79.9% efficiency at 600 W, which is, for us, a clear indication that this unit is really a 600 W part.

Voltages were closer to their nominal values (3% regulation) during tests one, two, and three. On the other tests, the +3.3 V output was outside this tighter regulation (between +3.15 V and +3.17 V), but still inside the proper range. The ATX12V specification says positive voltages must be within 5% of their nominal values, and negative voltages must be within 10% of their nominal values.

Noise and ripple levels were low, except the +5VSB output, which was close to the 50 mV limit at 45.8 mV during test six. Below you can see the results for the power supply outputs during test number six, with the unit delivering around 600 W. The maximum allowed is 120 mV for +12 V and -12 V outputs, and 50 mV for +5 V, +3.3 V and +5VSB outputs. All values are peak-to-peak figures.

Cougar RS 650 W power supply
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Figure 17: +12VA input from load tester during test six at 602.7 W (57.2 mV)

Cougar RS 650 W power supply
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Figure 18: +12VB input from load tester during test six at 602.7 W (52.8 mV)

Cougar RS 650 W power supply
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Figure 19: +5V rail during test six at 602.7 W (32.2 mV)

Cougar RS 650 W power supply
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Figure 20: +3.3 V rail during test six at 602.7 W (28 mV)

Let’s see what went wrong.

The Explosion

As explained, we tested two samples with the same results: The Cougar RS 650 W explodes if you pull more than 600 W from it at high temperatures. The components that burned were one of the switching transistors, one of the primary diodes, and one of the +12 V rectifiers. The video below was shot while we put the power supply to run our test number seven (see previous page) and, in Figure 21, you can see the primary diode that exploded.

Cougar RS 650 W power supply
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Figure 21: Primary diode exploded (compare it to the diode to its left)

Main Specifications

The main specifications for the Cougar RS 650 W power supply include:

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

Conclusions

The Cougar RS 650 W is, in reality, a 600 W power supply, as it explodes if you try to pull more than 600 W from it. We tested two samples, with the same results.

Users buying this unit probably won’t pull anywhere close to 600 W or 650 W. We believe that manufacturers must label power supplies with their true wattages. Therefore, we can’t recommend this unit.

It is important to understand that the manufacturer may not have done this on purpose. The RS 650 W looks like a textbook case of a power supply that was labeled at a room temperature of only 25° C (which we believe doesn’t represent a real-world scenario). As the ability to deliver current (and, thus, power) drops as temperature increases, it can’t deliver its labeled power at high temperatures. In cases like this, the power supply over power protection should have kicked in, which didn’t happen with the reviewed power supply.

Originally at http://www.hardwaresecrets.com/article/Cougar-RS-650-W-Power-Supply-Review/1323


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