PC Power & Cooling Silencer 750 Quad Power Supply Review
By Gabriel Torres on May 14, 2008


Introduction

Hardware Secrets Golden Award

Silencer 750 Quad is a 750 W power supply from PC Power & Cooling featuring a single +12 V rail, four auxiliary PCI Express power cables for video cards, active PFC, efficiency above 80% and the very traditional ATX looks, with a small 80 mm fan on the rear side. The manufacturer promises that this unit can deliver its labeled power at 40° C and has a maximum peak power of 825 W. Sounds promising, but can this unit really deliver 750 W? Let’s see.

What is really interesting about PC Power & Cooling is they test each unit individually at a Chroma 8000 load tester and include the report generated for the unit you bought inside the product box, as you can see in Figure 3.

It is available in two colors, red or black. The red version is also known as “CrossFire Edition.”

PC Power & Cooling Silencer 750 Quad
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Figure 1: PC Power & Cooling Silencer 750 Quad power supply.

PC Power & Cooling Silencer 750 Quad
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Figure 2: PC Power & Cooling Silencer 750 Quad power supply.

PC Power & Cooling Silencer 750 Quad
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Figure 3: Individual Chroma 800 report that came with the reviewed unit.

According to the report that came with our unit it could deliver 85% efficiency at full load and 830 W peak power. Of course we will see how much this unit will deliver under our own tests.

As we mentioned this power supply uses a regular 80 mm fan on its rear instead of a 120 mm or bigger fan on its bottom. This fan was surprisingly quiet during our tests and we could only hear it working when the unit was delivering its full 750 W (more about this later).

This power supply has active PFC, which provides a better usage of the power grid and allowing PC Power & Cooling to sell this product in Europe (read more about PFC on our Power Supply Tutorial). PC Power & Cooling says that this product has 83% efficiency. The higher the efficiency the better – an 80% efficiency means that 80% of the power pulled from the power grid will be converted in power on the power supply outputs and only 20% will be wasted. This translates into less consumption from the power grid (as less power needs to be pulled in order to generate the same amount of power on its outputs), meaning lower electricity bills.

The main motherboard cable uses a 24-pin connector (no support for 20-pin motherboards) and this power supply has one ATX12V connector and one EPS12V connector.

This power supply comes with nine peripheral power cables: two 6-pin auxiliary power cables for video cards, two 6/8-pin auxiliary power cables for video cards, two cables containing three standard peripheral power connectors each, one cable containing two standard peripheral power connectors and one floppy disk drive power connector and two cables with three SATA power connectors each.

The number of connectors provided by this power supply is adequate for a power supply from this range, but very high-end users may find that the number of SATA power connectors provided by this unit is not enough for their ultra high-end systems, especially now with optical drives also coming with SATA power connectors. It is always good to remind that you can convert any standard peripheral power plug into a SATA power plug using adapters (that don’t come with the power supply) and since this unit has eight standard peripheral power connectors the number of available connectors shouldn’t be an issue. We were only talking about the convenience of having more SATA power plugs without needing to use adapters.

On this power supply all wires are 18 AWG, which is ok, even though we personally prefer to see some 16 AWG wires being used on power supplies from this range.

On the aesthetic side PC Power & Cooling used nylon sleevings on all cables, coming from inside the power supply housing.

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

A Look Inside The Silencer 750 Quad

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.

PC Power & Cooling Silencer 750 Quad
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Figure 4: Overall look.

PC Power & Cooling Silencer 750 Quad
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Figure 5: Overall look.

PC Power & Cooling Silencer 750 Quad
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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 stage this power supply is flawless, providing two extra Y capacitors, one extra ferrite coil, one extra X capacitor and a ferrite bead attached to the main AC cable. This power supply also provides an X capacitor after the rectifying bridge.

PC Power & Cooling Silencer 750 Quad
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Figure 7: Transient filtering stage (part 1).

PC Power & Cooling Silencer 750 Quad
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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 Silencer 750 Quad.

Primary Analysis

On this page we will take an in-depth look at the primary stage of PC Power & Cooling Silencer 750 Quad. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBJ1506 rectifying bridge in its primary, which can deliver up to 15 A (rated at 100° C). As you can see in Figure 9 this bridge is attached to a heatsink. This component is clearly overspec'ed: at 115 V this unit 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 this component. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

PC Power & Cooling Silencer 750 Quad
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Figure 9: Rectifying bridge.

The active PFC circuit uses two SPW35N60C3 power MOSFET transistors, each one capable of handling up to 21.9 A in continuous mode at 100° C (or 34.6 A at 25° C; see the difference temperature makes) or 103.8 A in pulse mode at 25° C. These transistors are located on the same heatsink as the switching transistors.

On the switching section this power supply uses two SPP24N60C3 power MOSFET transistors in the traditional two-transistor forward configuration. Each transistor is capable of handling up to 15.4 A at 100° C in continuous mode (or 24.3 A at 25° C) or up to 72.9 A in pulse mode at 25° C.

PC Power & Cooling Silencer 750 Quad
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Figure 10: Active PFC transistors (left), active PFC diode and switching transistors (right).

The primary section of this power supply is controlled by a UCC28515DW integrated circuit, which is a PFC/PWM controller combo.  This integrated circuit is located on a small printed circuit board attached to the main printed circuit board.

PC Power & Cooling Silencer 750 Quad
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Figure 11: Active PFC/PWM controller combo.

Secondary Analysis

This power supply has four Schottky rectifiers on its secondary.

The +12 V output is produced by two STPS6045CW Schottky rectifiers connected in parallel, each supporting up to 60 A at 150° C (30 A per internal diode). The maximum theoretical current the +12 V 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 (which in this case is made by two 30 A diodes in parallel). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 86 A or 1,029 W for the +12 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.

The +5 V output is produced by one STPS60L30CW Schottky rectifier, which supports up to 60 A at 130° C (30 A per internal diode). The maximum theoretical current the +5 V 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 (which in this case is made by one 30 A diode). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 43 A or 214 W for the +5 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.

And the +3.3 V output is produced by another STPS60L30CW Schottky rectifier, which supports up to 60 A at 130° C (30 A per internal diode). Following the same math the unit would be able to deliver up to 43 A or 141 W at +3.3 V.

PC Power & Cooling Silencer 750 Quad
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Figure 12: +12 V rectifier, +5 V rectifier and +3.3 V rectifier. The other +12 V rectifier is on the other side of the heatsink.

This power supply uses an HY510N monitoring integrated circuit, which is in charge of the power supply protections, like OCP (over current protection). OCP was really activated, as we will talk about later.

PC Power & Cooling Silencer 750 Quad
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Figure 13: HY510N monitoring integrated circuit.

This power supply uses a very small semiconductor thermal sensor, located under the main transformer secondary, see Figure 14. This sensor is used to control the fan speed according to the power supply internal temperature and to shut down the power supply in an overheating situation, if the power supply implements over temperature protection (OTP), which isn’t the case of Silencer 750 Quad.

PC Power & Cooling Silencer 750 Quad
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Figure 14: Thermal sensor.

This power supply uses only Japanese electrolytic capacitors from Chemi-Con, which is great (Japanese capacitors are the best). The active PFC capacitor is rated at 85° C while the secondary capacitors are rated at 105° C.

Power Distribution

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

PC Power & Cooling Silencer 750 Quad
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Figure 15: Power supply label.

There is not much to talk about here. PC Power & Cooling uses single-rail configuration for ages. So instead of separating the +12 V outputs in several rails with independent over current protection (OCP) circuits – i.e., multi-rail configuration – the manufacturer added just one OCP circuit monitoring all +12 V outputs.

Now let’s see if this power supply can really deliver 750 W of power.

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 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.

+12V2 is the second +12V input from our load tester and since the reviewed power supply uses a single-rail configuration this input was also connected to the +12V1 rail.

Input

Test 1

Test 2

Test 3

Test 4

Test 5

+12V1

6 A (72 W)

11.5 A (138 W)

17 A (204 W)

22 A (264 W)

28 A (336 W)

+12V2

5 A (60 W)

11 A (132 W)

16 A (192 W)

22 A (264 W)

27 A (324 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 W)

+5VSB

1 A (5 W)

1.5 A (7.5 W)

2 A (10 W)

2.5 A (12.5 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)

0.8 A (9.6 W)

Total

6 A (72 W)

11.5 A (138 W)

17 A (204 W)

22 A (264 W)

28 A (336 W)

% Max Load

20.2%

40.1%

59.3%

79.2%

99.5%

Room Temp.

47.4° C

47.9° C

49.7° C

50.1° C

50.9° C

PSU Temp.

50.1° C

50.5° C

51.6° C

50.° C

51.3° C

Voltage Stability

Pass

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

Pass

AC Power

171 W

337 W

506 W

694 W

901 W

Efficiency

88.8%

89.1%

87.9%

85.6%

82.8%

Final Result

Pass

Pass

Pass

Pass

Pass

We were really impressed by this power supply.

First, it could really deliver its labeled power at 50° C.

Second, it achieved an outstanding efficiency, between 82.8% and 89.1%. In fact the only moment efficiency was below 85% was when the power supply was delivering its full load.

Third, voltage regulation was outstanding and during all our tests all outputs were within 3% of their nominal voltages – ATX specification defines that all outputs must be within 5% of their nominal voltages (10% for -12 V) –, including -12 V, which usually is not close to its nominal value, and also during our overload tests (see next page).

And fourth, even though noise and ripple weren’t the lowest we’ve seen around they were at  levels below the average, which is excellent. With the reviewed power supply delivering 750 W of power noise level at +12 V outputs was around 50 mV, at +5 V was at 18.6 mV and at +3.3 V was at 20.4 mV.  Just to remember, all values are peak-to-peak voltages and the maximum allowed set by ATX standard is 120 mV for +12 V and 50 mV for +5 V and +3.3 V.

Another thing we liked about this power supply was that noise didn’t increase with increase in load. Usually as we increase the power supply load noise also increases. Noise levels remained practically the same on our load tests.

PC Power & Cooling Silencer 750 Quad
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Figure 16: Noise at +12V1 input from load tester at 750 W.

PC Power & Cooling Silencer 750 Quad
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Figure 17: Noise at +12V2 input from load tester at 750 W.

PC Power & Cooling Silencer 750 Quad
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Figure 18: Noise at +5 V input from load tester at 750 W.

PC Power & Cooling Silencer 750 Quad
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Figure 19: Noise at +3.3 V input from load tester at 750 W.

Now let’s see if we could pull even more power from this unit.

Overload Tests

Before performing our overload tests we always like to test first if the over current protection (OCP) circuit is really active and at what level it is configured.

We could increase current on +12 V up to 64 A, above that the power supply shut down. It was great to see that OCP was configured at a value close to the maximum value for +12 V outputs printed on the power supply label (60 A).

So with our load tester pulling 64 A from +12 V, we started increasing current on +5 V and +3.3 V. The maximum we could pull from these two lines with the power supply still working was 10 A each. When we pulled more than that ripple skyrocketed to 275 mV. So the maximum we could pull from this power supply was:

Input

Maximum

+12V1

32 A (384 W)

+12V2

32 A (384 W)

+5V

10 A (50 W)

+3.3 V

1 A (33.3 W)

+5VSB

3 A (15 W)

-12 V

0.8 A (9.6 W)

Total

868 W

% Max Load

115.7%

Room Temp.

50.4° C

PSU Temp.

52.0° C

AC Power

1,079 W

Efficiency

80.4%

This is a really impressive result, because room temperature was at 50° C and efficiency was still above 80%. Noise stayed practically on the same level it was before with the unit delivering 750 W.

Short circuit protection (SCP) worked fine for both +5 V and +12 V lines.

And amazingly the fan of this power supply was really quiet. We could only hear it when the unit was pulling its full 750 W or more. Then it started to make a lot of noise.

Main Specifications

PC Power & Cooling Silencer 750 Quad power supply specs include:

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

Conclusions

We were really impressed by this power supply. It not only could deliver its labeled power at 50° C, but we could pull up to 868 W also at 50° C!

Efficiency was one of the highlights of this product during our tests. If you pull up to 80% of its labeled capacity (i.e., up to 600 W) you will have at least 85% efficiency, peaking almost 90% when you pull 40% of its capacity (300 W). We could see an efficiency of 82.8% when it was delivering 750 W, which isn’t bad at all! Even when we overloaded it efficiency was still above 80%.

It is a very quiet power supply if you run it below its maximum capacity.

Featuring a 5-year warranty (the product box says 3 years, but it is wrong), four video card power cables (two of them with 6/8-pin connectors) and a sufficient number of peripheral power connectors, this product is perfect for high-end users looking for a power supply on the 750 W-850 W range. And the best of all, it isn’t expensive for a power supply on this power range (it costs between USD 150 and USD 160 in the US), providing a terrific cost/benefit ratio for this kind of user.

Therefore PC Power & Cooling Silencer 750 Quad deserves no less than our “Golden Award” seal.

Originally at http://www.hardwaresecrets.com/article/PC-Power-and-Cooling-Silencer-750-Quad-Power-Supply-Review/553


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