Zalman has a complete line of power supplies from 360 W to 1,000 W. We decided to take a look at the simplest model, ZM360B-APS, which costs only around USD 60. Even though it is an entry-level power supply, it features active PFC, a 120 mm fan and two video card power connectors, so things looked pretty spec-wise. But can it really deliver its rated 360 W? Is this a really good product for Average Joe? Let’s see.
Figure 1: Zalman ZM360B-APS Power Supply.
Figure 2: Zalman ZM360B-APS Power Supply.
As you can see, this power supply uses a big 120 mm ball bearing fan on its bottom (the power supply is upside down on Figures 1 and 2) and a big mesh on the rear side where traditionally we have an 80 mm fan. We like this design as it provides not only a better airflow but the power supply produces less noise, as the fan can rotate at a lower speed in order to produce the same airflow as an 80 mm fan.
This power supply has active PFC, a feature not usually found on entry-level power supplies. PFC provides a better usage of the power grid and allows Zalman to sell this product in Europe (read more about PFC on our Power Supply Tutorial). As for efficiency, Zalman says that this product has a minimum 80% efficiency. Of course we will measure this to see if what the manufacturer claim is true. Keep in mind that more expensive power supplies have an efficiency of at least 80%. 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 20/24-pin connector and this power supply has one EPS12V connector that can be split into two ATX12V connectors.
This power supply comes with five peripheral power cables: one auxiliary power cable for video cards with two 6-pin connectors attached, two cables containing two standard peripheral power connectors and one floppy disk drive connector each and two cables with two SATA power connectors each. It also comes with a fan power adapter, allowing you to connect any fan using a small three-pin connector to any standard peripheral power plug.
Here Zalman ZM360B-APS is somewhat different from other entry-level power supplies we’ve seen recently (Seventeam ST-420BKV, Kingwin ABT-450MM, Thermaltake PurePower 430 NP and Huntkey Green Star 450 W): this power supply provides two 6-pin video card power connectors, while other units provide just one or none. Also, this product from Zalman has four SATA power connectors, which is perfect for today’s usage, while other entry-level products provide only two SATA power connectors.
We only didn’t like the way the two video card power connectors are installed. Instead of using two separated cables, they are connected together on the same cable. But this isn’t a serious issue for a power supply from this power range.
Figure 3: How the two 6-pin video card power connectors are connected to the unit.
On this power supply all wires are 18 AWG except the wires used on the video card power cable, which are 20 AWG (i.e. thinner). We’d like to see all wires 18 AWG.
On the aesthetic side Zalman used nylon sleeving on all cables, coming from inside the power supply housing.
This power supply is manufactured by SPI Electronics and on their website there is no model that is identical to ZM360B-APS, so it seems that this model is manufactured exclusively for Zalman.
Now let’s take an in-depth look inside this power supply.
[nextpage title=”A Look Inside The ZM360B-APS”]
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.
One interesting thing about this power supply is that it uses its housing as an extension to the secondary heatsink, as you can see on Figures 5 and 6. The manufacturer used thermal grease between the secondary heatsink and the power supply housing.
Figure 5: The power supply housing is also used as a heatsink.
Figure 6: The power supply housing is also used as a heatsink.
[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.< /p>
Even though this power supply has two additional Y capacitors on its transient filtering stage and two additional X capacitors and one additional ferrite coil after the rectifying bridge, it doesn’t have a MOV, which is essential to cut spikes coming from the power grid.
Figure 9: Transient filtering stage (part 1).
Figure 10: Transient filtering stage (part 2).
In the next page we will have a more detailed discussion about the components used in the ZM360B-APS.
[nextpage title=”Primary Analysis”]
We were very curious to check what components were chosen for the power section of this power supply and also how they were set together, i.e., the design used. We were willing to see if the components could really deliver the power announced by Zalman.
From all the specs provided on the databook of each component, we are more interested on the maximum continuous current parameter, given in ampères or amps for short. To find the maximum theoretical power capacity of the component in watts we need just to use the formula P = V x I, where P is power in watts, V is the voltage in volts and I is the current in ampères.
We also need to know under which temperature the component manufacturer measured the component maximum current (this piece of information is also found on the component databook). The higher the temperature, the lower current semiconductors can deliver. Currents given at temperatures lower than 50° C are no good, as temperatures below that don’t reflect the power supply real working conditions.
Keep in mind that this doesn’t mean that the power supply will deliver the maximum current rated for each component as the maximum power the power supply can deliver depends on other components used – like the transformer, coils, the PCB layout, the wire gauge and even the width of the printed circuit board traces – not only on the specs of the main components we are going to analyze.
For a better understanding of what we are talking here, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses one GBU606 rectifying bridge in its primary stage, which can deliver up to 6 A (rated at 100° C). This bridge is attached to the same heatsink where the switching transistors are located. This is more than adequate rating for a 360 W power supply. The reason why is that at 115 V this unit would be able to pull up to 690 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 552 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.
On the active PFC circuit two STP14NK50ZFP power MOSFET transistors are used, each one capable of handling up to 14 A at 25° C or 7.6 A at 100° C in continuous mode, or up to 48 A at 25° C in pulse mode. These transistors are located on a separated heatsink, together with the active PFC diode.
Figure 12: Active PFC transistors and diode.
On the switching section this power supply uses two FQPF9N50C power MOSFET transistors in two-transistor forward configuration. Each one of these transistors can deliver up to 9 A at 25° C or 5.4 A at 100° C in continuous mode, or up to 36 A at 25° C in pulse mode, which is the mode used. As mentioned, these transistors are located on the same heatsink as the rectifying bridge.
Figure 13: Switching transistors.
The primary section is controlled by a CM6800 integrated circuit, which is a very popular active PFC and PWM controller combo. It is located on a small printed circuit board attached to the main board.
Figure 14: PFC and PWM controller combo.
[nextpage title=”Secondary Analysis”]
This power supply has four Schottky rectifiers on its secondary using the same configuration used by high-end power supplies.
The +12 V output is produced by two MBR2060CT Schottky rectifiers connected in parallel, which support up to 20 A (10 A per internal diode) at 125° C each. 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 a MBRP3045N Schottky rectifier, which supports up to 30 A (15 A per diode) at 100° C 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 one 15 A diode). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 21 A or 107 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 another MBRP3045N Schottky rectifier, which supports up to 30 A (15 A per diode) at 100° C. Using the same math we would get a maximum theoretical power of 71 W for the +3.3 V output.
Figure 15: +3.3 V, +5 V and +12 V rectifiers.
This power supply uses separated filtering stages for each 12 V virtual rail, which is great.
This power supply uses a PS223 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. This IC also provides over voltage protection (OVP), under voltage protection (UVP) and over temperature protection (OTP), but not over power protection (OPP).
Figure 16: PS223 monitoring integrated circuit.
The thermal sensor is located under the secondary heatsink, as you can see in Figure 17 (we took this picture with the heatsink removed). 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. As we mentioned, the monitoring IC supports this protection and Zalman says this unit features this protection. We, however, couldn’t test this feature, as the power supply was always working very cool.
On this power supply all electrolytic capacitors are Taiwanese, from CapXon, with the active PFC capacitor rated at 85° C and the secondary capacitors rated at 105° C.
[nextpage title=”Power Distribution”]
In Figure 18, you can see the power supply label containing all the power specs.
Figure 18: Power supply label.
As you can see this power supply has two +12 V virtual rails. These rails are distributed as following:
- +12V1 (solid yellow wire): Main motherboard cable and all peripheral cables.
- +12V2 (yellow with black stripe wire): EPS12V/ATX12V cable.
We tested OCP circuit and it is really active as we will discuss later.
Now let’s see if this power supply can really deliver 360 W of power.
[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.
+12V2 is the second +12V input from our load tester and during our tests we connected the power supply EPS12V connector to it, which is the only thing connected to the power supply +12V2 virtual rail. Thus +12V1 and +12V2 inputs from our load tester was connected to the +12V1 and +12V2 rails from the power supply.
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.
|Input||Test 1||Test 2||Test 3||Test 4||Test 5|
|+12V1||2 A (24 W)||5 A (60 W)||7 A (84 W)||9 A (108 W)||11 A (132 W)|
|+12V2||2.5 A (30 W)||5 A (60 W)||7 A (84 W)||10 A (120 W)||13.5 A (162 W)|
|+5V||1 A (5 W)||2 A (10 W)||4 A (20 W)||5 A (25 W)||6 A (30 W)|
|+3.3 V||1 A (3.3 W)||2 A (6.6 W)||4 A (13.2 W)||5 A (16.5 W)||6 A (19.8 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)|
|-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||67.4 W||147.5 W||214.5 W||284.1 W||358.8 W|
|% Max Load||18.7%||41.0%||59.6%||78.9%||99.7%|
|Room Temp.||43.9° C||45.7° C||45.1° C||45.6° C||48.1° C|
|PSU Temp.||48.9° C||50.8° C||49.5° C||50.1° C||51.3° C|
|Ripple and Noise||Pass||Pass||Pass||Pass||Pass|
|AC Power||81.8 W||173 W||254 W||344 W||448 W|
The results for this power supply were really impressive, especially when we think that this is supposedly an entry-level power supply. After reviewing a lot of low-end power supplies that couldn’t achieve efficiency above 80% or deliver their rated power, we were really happy to see an entry-level power supply that is up-to-date with the current market needs.
First, this power supply could deliver its labeled power at 48° C, which is excellent.
Second, its efficiency was always above 80%, peaking 85% when delivering 40% of its rated power (around 150 W).
Voltage regulation during all our tests (including the overload tests we will present in the next page) was outstanding, with all outputs within 3% of their nominal voltages – ATX specification defines that all outputs must be within 5% of their nominal voltages – except on -12 V during tests one, two and three, where this output was at -11.38 V, -11.5 V and -11.63 V respectively. These numbers, however, are still inside the 10% margin that is set by the ATX spec for this output. Of course we always want to see values closer to the nominal voltage.
Ripple and noise are another highlight from this product, as they were far below the maximum set by ATX spec (120 mV for +12 V and 50 mV for +5 V and +3.3 V). During our test number five – i.e., with the power supply delivering 360 W – noise level at +12V1 was 25.4 mV, noise level at +12V2 was 18.4 mV, noise level at +5 V was 23 mV and noise level at +3.3 V was 28.8 mV. Impressive results.
Figure 19: Noise level at +12V1 with power supply delivering 360 W.
Figure 20: Noise level at +12V2 with power supply delivering 360 W.
Figure 21: Noise level at +5 V with power supply delivering 360 W.
Figure 22: Noise level at +3.3 V with power supply delivering 360 W.
Now let’s see if we could pull more power from this product.
[nextpage title=”Overload Tests”]
We were really curious to see how much power this unit could really deliver, because by the project used we suspected it could deliver far more than what was labeled.
In the table below you can follow the several overloading tests we conducted.
|Input||400 W||423 W||440 W||460 W||475 W|
|+12V1||14 A (168 W)||15 A (180 W)||15 A (180 W)||15 A (180 W)||15 A (180 W)|
|+12V2||14 A (168 W)||15 A (180 W)||15 A (180 W)||15 A (180 W)||15 A (180 W)|
|+5V||6 A (30 W)||6 A (30 W)||8 A (40 W)||10 A (50 W)||12 A (60 W)|
|+3.3 V||6 A (19.8 W)||6 A (19.8 W)||8 A (26.4 W)||10 A (33.3 W)||12 A (39.6 W)|
|+5VSB||2.5 A (12.5 W)||2.5 A (12.5 W)||2.5 A (12.5 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)|
|Total||400 W||422.8 W||440 W||457.8 W||475 W|
|% Max Load||111.1%||117.4%||122.2%||127.2%||131.9%|
|AC Power||500 W||536 W||564 W||594 W||623 W|
Let’s explain exactly what we did. First we tested to see if over current protection circuit was really enabled. In order to do that we conducted two tests. First we connected the main motherboard cable to our load tester and increased current on +12V1 until the power supply shut down. This happened at 17 A, so OCP on +12V1 was set at 16 A. Then we connected EPS12V connector back to +12V2 input from our load tester, configured +12V1 to pull just a small amount of current (1 A) and increased current on +12V2 until the power supply shut down. This again happened at 17 A, so both virtual rails had OCP up and running, configured to shut down the power supply if we pulled more than 16 A from any of these two rails.
During our overload tests we tried to pull 16 A from each rail at the same time but we couldn’t, the power supply would shut down, either because of the OCP circuit or because voltages were out of range and the OVP or UVP was entering in action. The maximum we could pull from the two +12 V rails at the same time was 15 A.
After setting them at 15 A we decided to pull more from +5 V and +3.3 V to see what was this power supply limit. We tried pulling a very high value on these two lines like 20 A each to see if this power supply had over load protection. The power supply wouldn’t turn on, but probably because voltages went out of spec and OVP or UVP entered in action, because this power supply does not have OPP – keep reading to understand how we know that.
The maximum we could set at +5 V and +3.3 V that kept the reviewed power supply still turning on was 17 A each. This made our power supply to deliver 517 W and consume 705 W from the wall, so efficiency was at 73.3%. The problem, however, is that after one minute the power supply died. When we opened it we tested all main components and to our surprise all tested ok, so no main semiconductor burned, and we couldn’t find what exactly burned (probably the transformer).
Because we could pull up to 44% over the power supply rated power, we know that this power supply didn’t have over load protection (OLP or OPP, these two acronyms mean the same thing).
During all our load tests noise level was within specs but we couldn’t capture the screens for you to see.
Short circuit protection (SCP) worked fine for both +5 V and +12 V lines.
This power supply is really quiet, even when delivering its full power.[nextpage title=”Main Specifications”]
Zalman ZM360B-APS power supply specs include:
- ATX12V 2.2
- Nominal labeled power: 360 W.
- Measured maximum power: 475 W.
- Labeled efficiency: 80% minimum.
- Measured efficiency: Between 80.1% and 85.3% at 115 V.
- Active PFC: Yes.
- Motherboard Power Connectors: One 24-pin connector and one EPS12V connector that can be split into two ATX12V connectors.
- Video Card Power Connectors: Two 6-pin connectors.
- Peripheral Power Connectors: Four, two cables with two standard peripheral power connectors and one floppy disk drive power connector each.
- SATA Power Connectors: Four, two cables with two SATA power connectors each.
- Protections: Over voltage (OVP, not tested), under voltage (UVP, not tested), over current (OCP, tested and working), over temperature (OTP, not tested) and short-circuit (SCP, tested and working).
- Warranty: Three years.
- Real manufacturer: SPI Electronics
- More Information: https://www.zalmanusa.com
- Average price in the US*: USD 60.00
* Researched at Shopping.com on the day we published this review.
After reviewing a lot of entry-level power supplies using complete obsolete designs it was a joy to see a low-end unit using an updated design with active PFC, power MOSFET transistors, four SATA power connectors (and not just two), two six-pin video card power connectors (and not only just one or even none), efficiency of at least 80% all the time and best of all, able to deliver its labeled power at 48° C.
Not only that. We could easily pull far more than 360 W from this unit. If Zalman wanted, they could have labeled this power supply as a 400 W unit still promising to deliver 80%+ efficiency. Above 400 W, however, efficiency dropped below 80%. But it is always good to know that your power supply can deliver far more than what is on the label, and with this unit we could pull up to 475 W with the unit working just fine. How about that?
For the average user that is building a mainstream PC, this power supply offers one of the best cost/benefit ratios on the market: it delivers not only what the manufacturer promises but more, it uses an updated design, brings the necessary amount of power connectors Average Joe will need and has a terrific price tag. What else do you need?
The only problems we can see with this power supply is the lack of a MOV on the transient filtering stage and the lack an overload protection circuit, and that is the only reason we are giving it our
“Silver Award” seal instead of our “Golden Award.” Anyhow, this is a fantastic product for the average user.
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