Power Distribution

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.

Now let’s 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 articleHardware 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.

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 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 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 through the roof (220 mV). We tested to see the maximum power this unit could deliver and the results are in the 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.

Now let’s 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 in 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.
Figure 14: Noise level at +12V1 with this power supply delivering 435.8 W.
Figure 15: Noise level at +12V2 with this power supply delivering 435.8 W.
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.

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 itsefficiency 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 twohard 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 reviewedpower 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 can be an option for the average user that doesn’t need a lot of power and doesn’t have money to buy a better product.

Source: http://www.hardwaresecrets.com/article/Cooler-Master-eXtreme-Power-Plus-460-W-RS-460-PMSR-A3-Power-Supply-Review/550/10