Introduction
Cooler Master has recently launched a new entry-level series of power supplies, eXtreme Power Plus. Products from this series are very simple, with optional passive PFC. We reviewed the 460 W model (RS-460-PMSR-A3), which costs only USD 40. Is this a good product for the average user? Can it really deliver its rated 460 W? Let’s see.
You need to pay attention as Cooler Master has two power supply series with similar names. The older series is called eXtreme Power and the power supplies from this series are presumably manufactured by Seventeam. The new series is called eXtreme Power Plus, with models being manufactured by AcBel Polytech. So even though the names of these series are similar, each series use a different internal design. Unfortunately on their website Cooler Master puts all power supplies from both series on the same page, making you to believe that all units use the same design.
To make things worse, there are four kinds of power supplies on the new eXtreme Power Plus series: the ones using an 80-mm fan on the rear of the unit (model names starting with “PMS”) and the ones using a 120-mm on the bottom of the unit (model names starting with “PCA”), and the ones without PFC (model names ending with “R”) and the ones with passive PFC (model names ending with “P”, targeted to the European market).
Thus for the 460 W power we have four models (PMSR, PMSP, PCAR and PCAP) and like we mentioned we reviewed the RS-460-PMSR-A3 model, which has no PFC and has an 80-mm fan on the rear.
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Figure 1: Cooler Master eXtreme Power Plus 460 W (RS-460-PMSR-A3) power supply.
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Figure 2: Cooler Master eXtreme Power Plus 460 W (RS-460-PMSR-A3) power supply.
The main motherboard cable uses a 20/24-pin connector and this power supply has one ATX12V connector.
This power supply comes with four peripheral power cables: one auxiliary power cable for video cards with one 6-pin connector, one cable containing three standard peripheral power connectors, one cable containing two standard peripheral power connectors and one floppy disk drive power connector and one cable with three SATA power connectors.
The number of power plugs provided by this power supply is sufficient for someone building an entry-level PC.
On this power supply all wires are 20 AWG, which are thinner than we would like to see. We think that all power supplies should use at least 18 AWG wires.
On the aesthetic side Cooler Master used a nylon sleeving only on the main motherboard cable, coming from inside the power supply housing.
Let’s now take an in-depth look inside this power supply.A Look Inside eXtreme Power Plus 460 W (RS-460-PMSR-A3)
We decided to disassemble this power supply to see how it looks like inside, what is the design used and what components are used. Please read our Anatomy of Switching Power Supplies tutorial to understand how a power supply works inside and to compare this power supply to others.
In this page we will have an overall look, while on the next pages we will discuss in details the quality and rating of the components used.
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Figure 3: Overall look.
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Figure 4: Overall look.
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Figure 5: Overall look.
Transient Filtering Stage
As we mentioned on other articles and reviews, the first place we like to take a look when opening a power supply to have a hint about its quality is its filtering stage. The recommend 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 than that, usually removing the MOV and the first coil.
On this stage this power supply is flawless, providing two Y capacitors, one X capacitor and one MOV more than required.
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Figure 6: Transient filtering stage (part 1).
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Figure 7: Transient filtering stage (part 2).
Now let’s have a more detailed discussion on the components used on eXtreme Power Plus 460 W.
Primary Analysis
Let’s now take an in-depth look on the primary stage from Cooler Master eXtreme Power Plus 460 W (RS-460-PMSR-A3). For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses two GBU605 rectifying bridges connected in parallel on its primary stage. Each bridge can deliver up to 6 A (rated at 100º C), for a total of 12 A at 100º C. This stage is clearly overspec’ed, as power supplies from this power range usually use only one 6 A or 8 A bridge. At 115 V this unit would be able to pull up to 1,380 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 1,104 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. The bridges don’t use a heatsink, which can lower the maximum current they can deliver.
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Figure 8: Rectifying bridges.
On the switching section this power supply uses two 2SK2749 power MOSFET transistors in parallel in a single-transistor forward configuration. Most modern power supplies use a different configuration, two-transistor forward, which is more efficient. Each 2SK2749 can drive up to 7 A in continuous mode or up to 21 A in pulse mode (which is the mode used), so the maximum current the switching section can drive is 14 A in continuous mode or 42 A in pulse mode. All values were measured at 25º C.
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Figure 9: Switching transistors.
Secondary Analysis
This power supply has six Schottky rectifiers on its secondary, two for each positive voltage output (+12 V, +5 V and +3.3 V).
The +12 V output is produced by two STPS2045CT Schottky rectifiers connected in parallel, each one supporting up to 20 A at 155º C (10 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 10 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 29 A or 343 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 another two STPS2045CT Schottky rectifiers in parallel, supporting up to 20 A at 155º C (10 A per internal diode) each. 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 two 10 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 29 A or 143 W for the +5 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.
The +3.3 V output is produced by two STPS20S100CT Schottky rectifiers in parallel, supporting up to 20 A at 150º C (10 A per internal diode) each. So the maximum theoretical current the +3.3 V output can deliver is of 29 A or 94 W, using the same math described above. As mentioned the real power this line can deliver depends on other factors.
On this power supply the -12 V is regulated using a 7912 integrated circuit, which is great and explains why the -12 V output was so stable during our tests. Usually power supplies don’t use a voltage regulator circuit for this output and this is why it is usually far away from its nominal -12 V value.
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Figure 10: +3.3 V, +5 V and +12 V rectifiers.
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Figure 11: -12 V voltage regulator and +12 V, +5 V and +3.3 V rectifiers.
The thermal sensor is located on the secondary heatsink, as you can see on Figure 11. This sensor is used to control the fan speed according to the power supply internal temperature.
This power supply uses a WT7527 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.
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Figure 12: Weltrend WT7527 monitoring integrated circuit.
On this power supply all electrolytic capacitors are rated at 85º C, using Thai capacitors from Elite on the voltage doubler circuit and Taiwanese capacitors from Ltec on the secondary.
Power Distribution
On Figure 13 you can see this power supply label containing all its power specs.
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Figure 13: Power supply label.
The power label says that the combined power for the two +12 V rails is 312 W and that combined power for the main positive outputs (+3.3 V, +5 V and +12 V) is 401.5 W. This is a joke, right? Because if the label is right, this is a 420 W power supply. And if the manufacturer knows that this is a 420 W unit, why they labeled this power supply as being a 460 W unit? Of course we will test this power supply to see what its real maximum capacity is.
As you can see this power supply has two +12 V virtual rails. These rails are distributed as following:
- +12V1: Main motherboard cable and all peripheral cables.
- +12V2: ATX12V connector.
This is a typical distribution for a dual-rail power supply.
Let’s now see if this power supply can really deliver 460 W of power.
Load Tests
We made 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 loads patterns, trying to pull around 20%, 40%, 60%, 80% and 100% of its labeled maximum capacity (under “% Max Load” we list the actual percentage that was used), watching how the reviewed unit behaved under each load. On the table below we list the load patterns we used and the results for each load.
For the 100% load test we used two patterns. On the first one, test number five, we respected the maximum combined limit for the two +12 V rails printed on the power supply label (312 W). In order to respect this limit, however, we were testing the power supply with more current on the +5 V and +3.3 V lines than we wanted. So we included a sixth pattern also pulling 460 W from the reviewed unit but pulling more current from +12 V and less current from +5 V and +3.3 V.
If you add all the powers listed for each test you may find a value different from what posted under “Total” below. Since each output can have a slight variation (e.g. +5 V output working at 5.10 V) the actual total amount of power being delivered is slightly different from the calculated value. On “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 during our tests we connected the power supply ATX12V connector to it. Since the ATX12V connector is the only device connected to the power supply +12V2 rail, on this test +12V1 and +12V2 inputs from our load tester were really connected to +12V1 and +12V2 rails.
Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 | Test 6 |
+12V1 | 3.5 A (42 W ) | 7 A (84 W) | 10 A (120 W) | 13 A (156 W) | 13 A (156 W) | 16 A (192 W) |
+12V2 | 3 A (36 W) | 6.5 A (78 W) | 10 A (120 W) | 13 A (156 W) | 13 A (156 W) | 16 A (192 W) |
+5V | 1 A (5 W) | 2 A (10 W) | 4 A (20 W) | 6 A (30 W) | 17 A (85 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) | 17 A (56.1 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) | 2.5 A (12.5 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) | 0.5 A (6 W) |
Total | 97.0 W | 188.9 W | 282.9 W | 371.1 W | Fail | 458.8 W |
% Max Load | 21.1% | 41.1% | 61.5% | 80.7% | 99.8% | 99.7% |
Room Temp. | 46.6º C | 46.4º C | 47.4º C | 47.6º C | 47.0º C | 48.8º C |
PSU Temp. | 50.1º C | 49.6º C | 50.1º C | 50.3º C | 50.7º C | 48.4º C |
Voltage Stability | Pass | Pass | Pass | Pass | Fail | Pass |
Ripple and Noise | Pass | Pass | Pass | Pass | Fail | Fail |
AC Power | 123 W | 229 W | 347 W | 469 W | Fail | 598 W |
Efficiency | 78.9% | 82.5% | 81.5% | 79.1% | Fail | 76.7% |
Final Result | Pass | Pass | Pass | Pass | Fail | Fail |
This power supply failed to deliver 460 W. The funny thing was that respecting the maximum combined power for the two +12 V rails as printed on the unit’s label (test five) the power supply wouldn’t turn on, as its over power protection entered in action, but pulling 460 W not respecting this information (test six) it turned on, but ripple was thru the roof (220 mV). We tested to see the maximum power this unit could deliver and the results are on next page.
Efficiency was good (i.e. above 80%) when we pulled between 40% and 60% of the power supply maximum labeled power (i.e. between 185 W and 280 W), dropping below 80% on tests one (97 W) and four (370 W). These results are not bad for a USD 40 power supply, especially when we think that other low-end units that we’ve reviewed like Thermaltake Purepower 430 W NP and Seventeam ST-420BKV achieved values far below those.
On the other hand 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 (as we showed before this unit uses a voltage regulator integrated circuit for this output, and this explains its good performance).
During all tests this power supply achieved ripple and noise levels within specs, but other good mainstream power supplies we’ve reviewed like Antec EarthWatts 500 W and Corsair VX450W achieved far better values here (below 20 mV on +12 V outputs, while on the reviewed power supply noise level at +12 V outputs were between 54 mV and 59 mV during test number four). 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.
Let’s now see how much power we could pull from this unit keeping it working inside ATX specs.
Overload Tests
From our basic testing we knew already that this power supply had both over current (OCP) and over power (OPP) protections and they were working just fine, as the power supply simply shut down when we tried to pull 460 W from it using our pattern number five, instead of burning.
So the first thing we wanted to see was at what level the over current protection (OCP) circuit was configured. To test this we simply removed the ATX12V cable from the load tester, leaving only cables that were connected to the power supply +12V1 rail installed. Starting from pattern number six we configured +12V1 to pull 20 A and the power supply wouldn’t turn on. We decreased this value to 19 A and the power supply would turn on. So OCP was active and configured to shut down the power supply if we pulled more than 19 A from any rail. This is great, because according to the power supply label each +12 V has a limit of 18 A, so OCP was configured really close to what was printed on the label. Several power supplies on the market have the OCP circuit configured with a value that is so high that it probably will never enter in action, so the power supply isn’t really protected.
Our next move was to discover what was the maximum amount of power this unit could deliver still working inside its specs.
Starting from pattern number six (see previous page) we decreased current on each +12 V rail by 1 A and the power supply would work inside ATX specs. The configuration we used is shown on the table below.
Input | Maximum |
+12V1 | 15 A (180 W) |
+12V2 | 15 A (180 W) |
+5V | 8 A (40 W) |
+3.3 V | 8 A (26.4 W) |
+5VSB | 2.5 A (12.5 W) |
-12 V | 0.5 A (6 W) |
Total | 435.8 W |
% Max Load | 94.7% |
Room Temp. | 50.0º C |
PSU Temp. | 49.8º C |
AC Power | 570 W |
Efficiency | 76.5% |
At this scenario noise and ripple increased a lot, but still inside ATX specs: 83.4 mV at +12V1, 80 mV at +12V2, 32.2 mV at +5 V and 15.6 mV at +3.3 V.
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Figure 14: Noise level at +12V1 with this power supply delivering 435.8 W.
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Figure 15: Noise level at +12V2 with this power supply delivering 435.8 W.
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Figure 16: Noise level at +5V with this power supply delivering 435.8 W.
Short circuit protection (SCP) worked fine for both +5 V and +12 V lines.
The fan used on this power supply is quiet when the power supply isn’t hot, but it starts spinning fast and producing a lot of noise when the power supply temperature is over 30º C.
Main Features
Cooler Master eXtreme Power Plus 460 W (RS-460-PMSR-A3) power supply main specs include:
- Nominal labeled power: 460 W.
- Measured maximum power: 435.8 W at 50º C.
- Labeled efficiency: 70% minimum.
- Measured efficiency: Between 76.5% and 82.5% at 115 V.
- Active PFC: No.
- Motherboard Power Connectors: One 24-pin connector and one ATX12V connector.
- Video Card Power Connectors: One 6-pin connector.
- Peripheral Power Connectors: Five, one cable with three standard peripheral power connectors and one cable with two connectors.
- Floppy Disk Drive Power Connectors: One.
- SATA Power Connectors: Three.
- Protections: Over voltage (OVP, not tested), over current (OCP, tested and working), over power (OPP, tested and working) and short-circuit (SCP, tested and working).
- Warranty: Five years.
- Real manufacturer: AcBel Polytech
- More Information: http://www.coolermaster.com
- Average price in the US*: USD 40.00
* Researched at Newegg.com on the day we published this review.
Conclusions
Even though this power supply can’t deliver its labeled power, it isn’t a bad product for its price tag and targeted audience. Its real power is close to its labeled power (430 W) and its efficiency isn’t bad for a low-end product. Plus it has all its protections up and running, a thing sometimes hard to find on cheap power supplies.
If you are building an entry-level PC with just one or two hard disk drives and just one video card – or even maybe with an on-board solution – this power supply is a good option.
It is better than other low-end products we’ve reviewed. Here is a quick comparison between Cooler Master eXtreme Plus 460 W and other power supplies below 500 W we’ve already reviewed:
- Thermaltake Purepower 430 W: costs the same thing but has a worse efficiency and can’t deliver 430 W (during our tests we could only pull up to 350 W from this Thermaltake unit), while eXtreme Power Plus 460 W can.
- Seventeam ST-420BKV: Cooler Master eXtreme Power Plus 460 W is also better than this unit, as it provides a higher efficiency and an auxiliary power cable for video cards.
- Kingwin ABT-450MM: Can deliver more power than the reviewed power supply, but on the other hand this model from Cooler Master has over power protection (OPP), feature not found on this model from Kingwin.
- Huntkey Green Star 450 W: Can’t deliver more than 360 W, even though it presents a higher efficiency than the reviewed unit. Doesn’t have over power protection and exploded when we try pulling 450 W from it.
- Zalman ZM360B-APS: See how things are funny. This model from Zalman can deliver more power than this model from Cooler Master model, even though it is labeled as a 360 W unit. The problem is that this unit from Zalman doesn’t have an over power protection circuit. This model from Zalman presented a higher efficiency but it is more expensive (USD 63) than this model from Cooler Master.
- Corsair VX450W: A terrific product, better than the reviewed power supply. It can deliver more power, has far better efficiency, has lower noise level, has all protections but costs the double.
In summary, the only real flaw from this product considering its price range is its wrong label; this power supply should be sold as a 430 W unit. Nonetheless we think this is a good product for the average user that doesn’t need a lot of power and wants to save money.
Originally at http://www.hardwaresecrets.com/article/550
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