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[nextpage title=”Introduction”]

We also like to review low-end products from time to time so people with a serious budget restriction can have an idea whether it is worthwhile to buy cheap products or not. Today we are going to take an in-depth look at Elite Power 400 W (RS-400-PSAR-J3) from Cooler Master. Can it really deliver its rated power? Is it worthwhile giving it a shot if you don’t have a lot of money to spend on a power supply? Let’s see.

This particular unit is manufactured by FSP, meaning that Cooler Master uses all sort of vendors for their power supplies. For example, most units from the eXtreme Power Plus are manufactured by AcBel Polytech, with some models from this series being manufactured by Seventeam. Cooler Master also uses other vendor for their other power supply series.

By the way, this unit has the same fantastic statement “As sealed stick was removed, lost or damaged, it shall be out of warranty validity” on its label as the members from eXtreme Power Plus series that are manufactured by a different company. So the author of this statement in Engrish is Cooler Master. When will they stop using on-line translators and hire someone that can speak English to write their labels?

Another interesting information from the label: “The +3.3 V & +5 V & +12 V total output shall not exceed 327.9 W.” Well, if you add this to the 12.5 W maximum power for the +5VSB output and the 9.6 W maximum power for the -12 V output we have a 350 W power supply…

Cooler Master Elite Power 400 W power supplyFigure 1: Cooler Master Elite Power 400 W power supply.

Cooler Master Elite Power 400 W power supplyFigure 2: Cooler Master Elite Power 400 W power supply.

Cooler Master Elite Power 400 W is 5 ½” (140 mm) deep, using a 120 mm fan on its bottom. This unit does not feature a PFC circuit, as you can see by the presence of a 115 V/230 V switch in Figure 1, being based on the outdated half-bridge topology.

No modular cabling system is provided and cables don’t have a nylon protection. Only the ATX12V/EPS12V cable use 18 AWG wires. All other wires are 20 AWG, i.e., thinner than recommended.

The cables included are:

  • Main motherboard cable with a 20/24-pin connector,17 3/8” (44 cm) long.
  • One cable with two ATX12V connectors that together form one EPS12V connector, 20 ½” (52 cm) long.
  • One cable with one six-pin connector for video cards, 18 7/8” (48 cm) long.
  • Two cables with two SATA power connectors each, 16” (41 cm) to the first connector, 4 ¾” (12 cm) between connectors).
  • One cable with three standard peripheral power connectors and one floppy disk drive power connector, 16 ½” (42 cm) to the first connector, 4 ¾” (12 cm) between connectors.

This configuration is compatible with a low-end 400 W product.

Cooler Master Elite Power 400 W power supplyFigure 3: Cables.

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

[nextpage title=”A Look Inside The Cooler Master Elite Power 400 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.

Cooler Master Elite Power 400 W power supplyFigure 4: Overall look.

Cooler Master Elite Power 400 W power supplyFigure 5: Overall look.

Cooler Master Elite Power 400 W power supplyFigure 6: Overall look.

[nextpage title=”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. 

Even though this is an entry-level power supply, it has all the required components on this stage, including two MOV’s (installed between the two electrolytic capacitors from the voltage doubler, not shown on the picture below).

Cooler Master Elite Power 400 W power supplyFigure 7: Transient filtering stage.

In the next page we will have a more detailed discussion about the components used in the Cooler Master Elite Power 400 W.

[nextpage title=”Primary Analysis”]

On this page we will take an in-depth look at the primary stage of Cooler Master Elite Power 400 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBU806 rectifying bridge, which supports up to 8 A at 100° C if a heatsink is used, which is not the case, or up to 3.5 A at 100° C if a heatsink isn’t used. At 115 V this unit would be able to pull up to 403 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 322 W without burning itself out. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

Cooler Master Elite Po
wer 400 W power supplyFigure 8: Rectifying bridge.

This unit is based on the obsolete half-bridge topology using two 2SD209L power NPN transistors on its switching section. Each transistor is capable of handling up to 12 A at 25° C. Unfortunately the manufacturer does not provide the current limit at 100° C.

Cooler Master Elite Power 400 W power supplyFigure 9: Switching transistors.

The switching transistors are controlled by an FSP3528 PWM controller, which is located on the secondary from the power supply. As you can see, this circuit is a half-bridge PWM controller that was relabeled by FSP and we are not sure of what circuit it is derived from (the pinout is different from other 20-pin half-bridge PWM controllers we know, like SD6109 and SG6105).

Cooler Master Elite Power 400 W power supplyFigure 10: PWM controller.

The two electrolytic capacitors from the voltage doubler are from Teapo and labeled at 85° C.

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

[nextpage title=”Secondary Analysis”]

This power supply has four Schottky rectifiers on 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. Since this unit is based on the half-bridge topology, the duty cycle used is of 50%.

The +12 V output is produced by two HBR16200 Schottky rectifiers connected in parallel, each one supporting up to 16 A (8 A per internal diode at 150° C, 0.93 V maximum voltage drop – which is pretty high, meaning lower efficiency), giving us a maximum theoretical current of 32 A or 384 W for the +12 V output.

The +5 V output is produced by one SBL2045CT Schottky rectifier, which supports up to 20 A (10 A per internal diode at 95° C), giving us a maximum theoretical current of 20 A or 100 W for the +5 V output.

The +3.3 V output is produced by one MBR3045CT Schottky rectifier, which supports up to 30 A (15 A per internal diode at 130° C, maximum voltage drop of 0.82 V), giving us a maximum theoretical current of 30 A or 99 W for the +3.3 V output.

All these numbers are theoretical. The real amount of current/power each output can deliver is limited by other components, especially by the coils used on each output.

Cooler Master Elite Power 400 W power supplyFigure 11: +3.3 V, +12 V and +5 V rectifiers.

The outputs are monitored by the FSP3528 integrated circuit shown in Figure 10. Since we couldn’t figure out which circuit this product was renamed from we can’t tell what protections it really supports.

The electrolytic capacitors from the secondary are also from Teapo.

[nextpage title=”Power Distribution”]

In Figure 12, you can see the power supply label containing all the power specs.

Cooler Master Elite Power 400 W power supplyFigure 12: Power supply label.

As you can see, according to the label this unit has two +12 V rails. Inside the unit we could see two shunts (current sensors) attached to each +12 V rail. The two rails are divided like this:

  • +12V1 (solid yellow wire): ATX12V/EPS12V cable, peripheral connectors and SATA power connectors.
  • +12V2 (yellow with black stripe wire): Main motherboard cable and video card auxiliary power connector.

This distribution is good since it separates the CPU (ATX12V/EPS12V) from the video card.

Now let’s see if this power supply can really deliver 400 W.

[nextpage title=”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 this test the +12VA input was connected to the power supply +12V1 and +12V2 rails, while +12VB was connected to the power supply +12V1 rail (EPS12V connector).

Input Test 1 Test 2 Test 3 Test 4 Test 5
+12VA 2.5 A (30 W) 5.5 A (66 W) 8 A (96 W) 10.5 A (126 W) 14 A (168 W)
+12VB 2.5 A (30 W) 5.5 A (66 W) 8 A (96 W) 10.5 A (126 W) 13 A (156 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 (5 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 A (5 W) 1.5 A (7.5 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) 0.5 A (6 W) 0.5 A (6 W)
Total 78.9 W 158.3 W 236.8 W 309.6 W 395.4 W
% Max Load 19.7% 39.6% 59.2% 77.4% 98.9%
Room Temp. 46.0° C 46.0° C 46.5° C 47.5° C 45.4° C
PSU Temp. 51.9° C 51.5° C 51.1° C 51.8° C 52.4° C
Voltage Regulation Pass Pass Pass Pass Pass
Ripple and Noise Pass Pass Pass Pass Pass
AC Power 101.3 W 195.8 W 296.4 W 398
.1 W
539.0 W
Efficiency 77.9% 80.8% 79.9% 77.8% 73.4%
AC Voltage 114.9 V 114.4 V 113.4 V 112.2 V 110.5
Power Factor 0.559 0.624 0.645 0.66 0.673
Final Result Pass Pass Pass Pass Pass

Cooler Master Elite Power 400 W can really deliver its labeled power at high temperatures.

If fact we had a few good surprises with this unit.

Usually ultra low-end power supplies (i.e., cheap units) present efficiency way below 80%, but with this one efficiency was touching 80% when we pulled between 40% and 60% from its labeled capacity (i.e., between 160 W and 240 W). At full load, however, efficiency dropped to around 73%.

Voltage regulation was the highlight from this unit. All positive voltages were within 3% of their nominal values all the times, which is great, since the ATX12V specification allows a 5% tolerance for these outputs.

The only real problem with this power supply is the high noise and ripple levels, which is kind of expected on low-end units. Although high, they were still inside specs. During test five noise level at +12VA touched the 120 mV limit, as you can see below. The maximum allowed is 120 mV on +12 V and 50 mV on +5 V and +3.3 V. All these numbers are peak-to-peak figures.

Cooler Master Elite Power 400 W power supplyFigure 13: +12VA input from load tester at 395.4 W (120.0 mV).

Cooler Master Elite Power 400 W power supplyFigure 14: +12VB input from load tester at 395.4 W (113.4 mV).

Cooler Master Elite Power 400 W power supplyFigure 15: +5 V rail with power supply delivering 395.4 W (30.6 mV).

Cooler Master Elite Power 400 W power supplyFigure 16: +3.3 V rail with power supply delivering 395.4 W (27.6 mV).

Let’s see if this unit can deliver more than 400 W.

[nextpage title=”Overload Tests”]

Below you can see the maximum we could pull from this unit. If we increased one amp at any given output the unit would shut down, showing that one of its protections entered in action, which is great.

Input Overload Test
+12VA 15 A (180 W)
+12VB 14 A (168 W)
+5V 8 A (40 W)
+3.3 V 8 A (26.4 W)
+5VSB 2 A (10 W)
-12 V 0.5 A (6 W)
Total 419.4 W
% Max Load 104.9%
Room Temp. 42.4° C
PSU Temp. 44.6° C
AC Power 571.0 W
Efficiency 73.5%

[nextpage title=”Main Specifications”]

Cooler Master Elite Power 400 W power supply specs include:

  • ATX12V 2.3
  • Nominal labeled power: 400 W.
  • Measured maximum power: 419.4 W at 42.4° C.
  • Labeled efficiency: Above 70%
  • Measured efficiency: Between 73.4% and 80.8% at 115 V (nominal, see complete results for actual voltage).
  • Active PFC: No.
  • Modular Cabling System: No.
  • Motherboard Power Connectors: One 20/24-pin connector and two ATX12V connectors that together form an EPS12V connector.
  • Video Card Power Connectors: One six-pin connector.
  • SATA Power Connectors: Four in two cables.
  • Peripheral Power Connectors: Three in one cable.
  • Floppy Disk Drive Power Connectors: One.
  • Protections: over voltage (OVP), over current (OCP), over power (OPP) and short-circuit (SCP).
  • Warranty: Two years.
  • Real Manufacturer: FSP
  • More Information: https://www.coolermaster-usa.com
  • Average price in the US*: USD 30.00.

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

[nextpage title=”Conclusions”]

Although with performance not comparable to more expensive models, Elite Power 400 W can really deliver its labeled wattage (in fact we could pull up to 420 W from it), provides an outstanding voltage regulation, it is very inexpensive and won’t damage your computer.

When we pulled between 40% and 60% from its labeled wattage (between 160 W and 240 W) efficiency touched 80%, which is certainly a good news, since most low-end units provide efficiency below 80% all the times.

But since it didn’t show efficiency above 80% all the times and noise and ripple levels were very high (touching the 120 mV limit on +12 V output when we pulled 400 W from it), we can’t recommend it.