Introduction

UCP 700 W (also known as RS700-AAAAA3-US) from Cooler Master uses a DC-DC converter on its secondary, i.e., it is basically a +12 V power supply using two small power supplies to convert the main +12 V output into +5 V and +3.3 V. This is the same principle behind power supplies from Antec Signature, Seasonic M12D, Corsair HX (750W and up) series and at least with these other units it proved to deliver very high efficiency. UCP 700 W is 80 Plus Silver certified, meaning that it provides at least 85% efficiency at full load and at least 88% efficiency during typical (50% load) operation. By the way, UCP stands for Ultimate Circuit Protection.

The real manufacturer behind Cooler Master UCP series is Acbel.

As you can see on Figures 1 and 2 a great deal of attention was given to the external aspect of the power supply, which uses a special coating that makes it to look like a military-grade component.

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Figure 1: Cooler Master UCP 700 W power supply.

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Figure 2: Cooler Master UCP 700 W power supply.

UPC 700 W is a small unit, being 6” (15 cm) deep, using a 120 mm fan on its bottom and featuring active PFC, of course. It does not have a modular cabling system.

All cables are protected by a nylon sleeving and they all come from inside the power supply housing. Cables are somewhat long, measuring 19 11/16” (50 cm) between the housing and the first connector on the cable (the ATX12V/EPS12V cable is longer, measuring 23 5/8” or 60 cm), and 5 ½” (140 mm) between connectors on cables with more than one connector. All wires are 18 AWG, which is the correct gauge to be used.

The cables included are:

• Main motherboard cable with a 24-pin connector (no 20-pin option).
• One cable with one EPS12V connector and one ATX12V connector.
• Two auxiliary power cables for video cards with one six/eight-pin video card auxiliary power connector and one six-pin video card auxiliary power connector each.
• Two auxiliary power cables for video cards with one six-pin video card auxiliary power connector each.
• Two SATA power cables with three SATA power connectors each.
• One peripheral power cable with three standard peripheral power plugs.
• One peripheral power cable with two standard peripheral power plugs and one floppy disk drive power connector.

Even though this power supply brings six power connectors for video cards, there are some drawbacks on the configuration used. From these six connectors, four are six-pin and two are eight-pin, without the option to be converted into six-pin models. You won’t have any trouble setting up a two-way SLI or CrossFire configuration, but these connectors limit the kind of video cards you may have when installing a high-end three-way SLI or CrossFire configuration: you can only use this power supply with three high-end video cards only if the first two have one six-pin and one eight-pin connector and if the third one has two six-pin connectors. Since this probably won’t be the case, you will need to either convert the two eight-pin connectors into six-pin connectors or one of the six-pin connectors into an eight-pin one. In either case you will need to buy these adapters, as UCP 700 W doesn’t come with them.

Also the eight-pin connectors are sharing the cables with six-pin connectors, which is not the best configuration. For the best performance each connector should use individual cables.

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Figure 3: Cables.

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

A Look Inside The UCP 700 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.

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Figure 4: Overall look.

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Figure 5: Overall look.

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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.

This stage from UCP 700 W is flawless, providing four Y capacitors and one X capacitor more than required.

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Figure 7: Transient filtering stage (part 1).

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Figure 8: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion of the components used in the Cooler Master UCP 700 W.

Primary Analysis

On this page we will take an in-depth look at the primary stage of Cooler Master UCP 700 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU806 rectifying bridges connected in parallel, each one capable of delivering up to 8 A at 100º C. This section is clearly overspec’ed: at 115 V this unit would be able to pull up to 1,840 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 1,472 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.

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Figure 9: Rectifying bridges.

On the active PFC circuit two SPP20N60C3 power MOSFET transistors are used, each one capable of delivering up to 20.7 A at 25º C or 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 resistance of 190 mΩ when turned on, a characteristic called RDS(on). This number indicates the amount of power that is wasted, so the lower this number the better, as less power will be wasted thus increasing efficiency.

This power supply uses two electrolytic capacitors to filter the output from the active PFC circuit. The use of more than one capacitor here has absolute nothing to do with the “quality” of the power supply, as laypersons may assume (including people without the proper background in electronics doing power supply reviews around the web). Instead of using one big capacitor, manufacturers may choose to use two or more smaller components that will give the same total capacitance, in order to better accommodate space on the printed circuit board, as two or more capacitors with small capacitance are physically smaller than one capacitor with the same total capacitance. UCP 700 W uses one 330 µF x 400 V and one 270 µF x 400 V capacitor connected in parallel; this is equivalent of one 600 µF x 400 V capacitor.

These capacitors are Japanese, from Chemi-Con and are labeled at 85º C.

In the switching section, another two SPP20N60C3 power MOSFET transistors are used on the traditional two-transistor forward configuration. The specs for these transistors are already published above.

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Figure 10: Switching transistors, active PFC diode and transitor.

The primary is controlled by a FAN4800I PFC/PWM combo controller.

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Figure 11: PFC/PWM combo controller.

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

Secondary Analysis

This power supply uses nine STPS30L60CT Schottky rectifiers on its secondary and each one is capable of handling up to 30 A (15 A per internal diode at 130º C, maximum voltage drop of 0.75 V). Eight of these rectifiers are in charge of producing the +12 V output, with +5 V and +3.3 V being generated from the +12 V output using separated DC-DC converters (i.e., small switching power supplies) located on two small printed circuit boards. As mentioned before, this is the same design used by Antec Signature, Seasonic M12D and Corsair HX (750W and up) power supply series.

The ninth rectifier available is in charge of the +5VSB output. Also on the secondary heatsink there is a 7912 voltage regulator, in charge of the -12 V output.

Four of the rectifiers are in charge of the direct rectification, while the other four are in charge of the “freewheeling” part of the rectification process (i.e., discharging the coil).

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%.

Thus the secondary from UCP 700 W has a maximum theoretical current of 171 A (30 A x 4 / 0.70). This maximum theoretical current limit is for the whole secondary, since +5 V and +3.3 V are also produced from the +12 V output. The practical limit will depend on other factors, but mainly on the coils used and on the design from the small DC-DC converter used to generate the +5 V and +3.3 V outputs. If this 171 A was solely pulled from the +12 V outputs, this would give us 2,052 W.

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Figure 12: Rectifiers.

In Figure 13, you can see the two DC-DC converters in charge of the +5 V and +3.3 V outputs. As you can see, their outputs are filtered using solid aluminum caps. Each converter is based on an APW7073 controller and uses three FDD8896 power MOSFET transistors, which present a maximum RDS(on) of only 6.8 mΩ.

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Figure 13: DC-DC converters.

The outputs are monitored by a WT7527 integrated circuit, which supports under voltage (UVP), over voltage (OVP) and over current (OCP). Any other protection that this unit may have is implemented outside this integrated circuit.

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Figure 14: Monitoring integrated circuit.

Electrolytic capacitors from the secondary are from Ltec, a Taiwanese manufacturer. We think the manufacturer should have added Japanese capacitors here, since the electrolytic capacitors from the primary are Japanese and the capacitors from the +5 V and +3.3 V outputs are solid.

Power Distribution

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

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Figure 15: Power supply label.

This power supply has four virtual rails, distributed like this:

• +12V1 (yellow with black stripe wire): Main motherboard cable, SATA and peripheral power connectors.
• +12V2 (solid yellow wire): ATX12V/EPS12V cable.
• +12V3 (yellow with blue stripe wire): One of the video card cables with one six-pin connector and one of the video card cables with one six-pin connector and one eight-pin connector.
• +12V4 (yellow with green stripe wire): One of the video card cables with one six-pin connector and one of the video card cables with one six-pin connector and one eight-pin connector.

This is the standard distribution for a four-rail power supply.

Now let’s see if this power supply can really deliver 700 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.

+12V1 and +12V2 are the two independent +12V inputs from our load tester and during our tests the +12V1 input was connected to the power supply +12V1 and +12V3 rails and the +12V2 input was connected to the power supply +12V2 rail.

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12V1	5 A (60 W)	11 A (132 W)	16 A (192 W)	21 A (252 W)	25 A (300 W)
+12V2	5 A (60 W)	10 A (120 W)	15 A (180 W)	20 A (240 W)	25 A (300 W)
+5V	1 A (5 W)	2 A (10 W)	4 A (20 W)	6 A (30 W)	10 A (50 W)
+3.3 V	1 A (3.3 W)	2 A (6.6 W)	4 A (13.2 W)	6 A (19.8 W)	10 A (33 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)	0.5 A (6 W)
Total	138.9 W	280.8 W	418.4 W	554.9 W	696.7 W
% Max Load	19.8%	40.1%	59.8%	79.3%	99.5%
Room Temp.	45.1º C	46.9º C	48.7º C	47.8º C	49.9º C
PSU Temp.	45.7º C	47.1º C	49.2º C	50.2º C	51.1º C
Voltage Stability	Pass	Pass	Pass	Pass	Pass
Ripple and Noise	Pass	Pass	Pass	Failed on -12 V and +5VSB	Failed on +12 V, -12 V and +5VSB
AC Power	163.4 W	324.2 W	486.0 W	654.0 W	842.0 W
Efficiency	85.0%	86.6%	86.1%	84.8%	82.7%
AC Voltage	111.2 V	110.6 V	109.7 V	107.1 V	104.9 V
Power Factor	0.983	0.987	0.990	0.993	0.994
Final Result	Pass	Pass	Pass	Pass	Pass

Cooler Master UCP 700 W could really deliver its labeled power at 50º C, which is great.

The highlight from UCP 700 W is clearly efficiency, which was between 84.8% and 86.6% when we pulled up to 80% from its labeled load (i.e., up to 560 W). At full load (700 W) efficiency dropped to 82.7%, still a good number. It is important to keep in mind that we use a more rigorous methodology then the 80 Plus organization, especially regarding the temperature: they collect data at 23º C (a temperature impossible to be achieved inside a PC), while we collect data at a room temperature of at least double this number (which we consider more realistic; the higher the temperature, the lower the efficiency). This explains why even though this unit is 80 Plus Silver certified we saw efficiency of 82.7% and not 85% as expected.

All voltages were within 3% of their nominal values, except -12 V during test number one (3.5%, still inside the 10% margin this output has) and +5 V during test number five (4%, still inside the 5% margin this output has).

The main problem with Cooler Master UCP 700 W is electrical noise. Noise on -12 V was always high, starting at 76.4 mV during test number one and increasing until it got above the maximum allowed (120 mV) on tests number four (125.8 mV) and five (148.6 mV). Noise on +5VSB was touching the 50 mV limit on test number three (45.6 mV) and surpassed it during tests four (55.6 mV) and five (86.2 mV). These results alone wouldn’t be much of a problem, but +12 V was also very noisy, jumping from around 80 mV on test number three, to around 100 mV during test four and surpassing the 120 mV limit during test number five (124.4 mV on +12V1 and 129.4 mV on +12V2). Noise level on +5 V and +3.3 V outputs were within the proper range, though. All values are peak-to-peak and below you can see the main outputs during test five.

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Figure 16: +12V1 input from load tester at 696.7 W (124.4 mV).

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Figure 17: +12V2 input from load tester at 696.7 W (129.4 mV).

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Figure 18: +5V rail with power supply delivering 696.7 W (20.8 mV).

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Figure 19: +3.3 V rail with power supply delivering 696.7 W (26.2 mV).

We tested the over current protection circuit by increasing current on +12V2 rail until the power supply would shut down. This happened when we tried to pull more than 32 A from it.

For our traditional overload tests we increase currents while maintaining all outputs inside the proper range as set by the ATX specification. Since this unit was already with noise levels outside the maximum allowed when delivering 700 W, we decided not to overload it.

Main Specifications

Cooler Master UCP 700 W power supply specs include:

• ATX12V 2.3
• EPS12V2 2.92
• Nominal labeled power: 700 W.
• Measured maximum power: 696.7 W at 49.9º C.
• Labeled efficiency: Above 87% (80 Plus Silver certified)
• Measured efficiency: Between 82.7% and 86.6% at 115 V (nominal, see complete results for actual voltage).
• Active PFC: Yes.
• Modular Cabling System: No.
• Motherboard Power Connectors: One 24-pin connector and two ATX12V connectors that together form an EPS12V connector.
• Video Card Power Connectors: Four six-pin connectors and two eight-pin connectors.
• Peripheral Power Connectors: Five in two cables.
• Floppy Disk Drive Power Connectors: One.
• SATA Power Connectors: Six in two cables.
• Protections: Over voltage (OVP, not tested), under voltage (UVP, not tested), over current (OCP, tested and working), over power (OPP, not tested), over temperature (OTP, not tested) and short-circuit (SCP, tested and working).
• Warranty: Five years.
• More Information: http://www.coolermaster-usa.com
• Average price in the US*: USD 120.00.

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

Conclusions

Cooler Master UCP 700 W can really deliver its labeled power at 50º C and provides high efficiency of up to 86.6%.

The manufacturer says this product can deliver efficiency of at least 87%, which is simply not true. The manufacturer, however, didn’t say how they measure this (probably at 230 V, where power supplies reach higher efficiency) and also didn’t say under which load (e.g., typical, full, etc).

Although this product is 80 Plus Silver certified, we got only 82.7% efficiency when pulling 700 W from it. It is important to keep in mind that we use a more rigorous methodology then the 80 Plus organization, especially regarding the temperature: they collect data at 23º C (a temperature impossible to be achieved inside a PC), while we collect data at a room temperature of at least double this number (which we consider more realistic; the higher the temperature, the lower the efficiency). This explains the difference.

One thing we didn’t like about this power supply was the video card cable configuration, which does not allow you to run three-way SLI or CrossFire with high-end video cards without using adapters, even though this power supply has six video card power connectors. This happens because the product has four six-pin connectors and two eight-pin connectors. Cooler Master should have used instead only six/eight connectors, what would solve this compatibility issue.

The bad about UCP 700 W is the high electrical noise level at +12 V when the unit is delivering 700 W, above the maximum allowed.

Even though it has a secondary design similar to Antec Signature, Seasonic M12D and Corsair HX (750W and up), it simply cannot deliver the same quality level, and this explains its lower price tag (USD 120 in the USA).

It is an attractive product because of its higher efficiency compared to other products on the same price range, even though it produces a higher electrical noise level compared to other products around. If you understand UCP 700 W limitations and they don’t bother you, it can be a good option.