Zalman ZM460B-APS 460 W Power Supply Review
By Gabriel Torres on December 19, 2008
APS is the entry-level power supply series from Zalman, targeted to users that want a good power supply at an affordable price, featuring active PFC, 120 mm fan but no modular cabling system as other units from this manufacturer, what helps lowering the price from this series. We have already tested the 360 W model from this series, which achieved excellent results. Is the 460 W also a good product? Let’s see.
This power supply is very small, being 5 ½” (140 mm) deep, and as mentioned featuring a 120 mm fan on its bottom and active PFC circuit, allowing Zalman to market this product in Europe.
Since this product does not have a modular cabling system, all cables come from inside the power supply housing, all using a nylon protection that comes from inside the unit.
The main motherboard cable uses a 20/24-pin connector and ZM460-APS has two ATX12V connectors that together form an EPS12V connector. Even though these connectors are available on the same cable and protected by the same nylon sleeving, they use individual wires, so they act as being available on individual cables, which is the best configuration.
This power supply comes with one cable containing two 6-pin auxiliary power plugs for video cards. For a better current/power distribution we prefer when these connectors are attached to individual cables and not sharing the same cable.
This unit comes with two cables containing two standard peripheral power plugs and one floppy disk drive power plug each and two cables containing two SATA power plugs each.
Even though the number of plugs is enough to a mainstream PC, we think it would be better if this unit had at least two more peripheral power plugs and two more SATA power plugs.
All wires are 18 AWG, which is the correct gauge to be used nowadays.
ZM460-APS also comes with an adapter with speed selection for fans with 3-pin connectors. This adapter, which can be installed on any peripheral power plug, provides two outputs: one with +12 V (full speed) and another with +5 V (a little bit less than half-speed).
Like all other power supplies from Zalman, ZM460B-APS is manufactured by FSP. This manufacturer is also in charge of some power supplies from OCZ (GameXStream and StealthXStream series) and SilverStone (Strider series).
By the way, on our review from SilverStone Strider ST50F we left a question answered, pending our review on Zalman ZM460B-APS: is SilverStone Strider ST50F and Zalman ZM460B-APS the same power supply with a different label? The answer is yes. Even though some semiconductors are different, they have the exact same specs. The only difference is the number of peripheral power plus: SilverStone’s model has six peripheral power plugs and six SATA power plugs, while Zalman’s have only four of each.
As you would image, this power supply uses the same project as Zalman ZM360B-APS, which we have already reviewed, but with stronger semiconductors, as you would imagine. The project from these two power supplies and from Strider ST50F is also very similar to the one used on Zalman HP series, which have a few details changed to support higher currents/power, plus the addition of a modular cabling system.
During our internal analysis we will be comparing the components used on ZM460B-APS to the ones used on ZM360B-APS and SilverStone Strider ST50F.
Now let’s take an in-depth look inside this power supply.
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.
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 power supply has one extra X capacitor and one extra Y capacitor, plus two X capacitors and one ferrite coil after the rectifying bridge, however it doesn’t have a MOV, which is the component is charge of removing spikes coming from the power grid.
In the next page we will have a more detailed discussion about the components used in the ZM460-APS.
On this page we will take an in-depth look at the primary stage of Zalman ZM460-APS. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses one GBU805 rectifying bridge in its primary, capable of delivering up to 8 A at 100° C. Zalman ZM360-APS uses a bridge with lower current limit (GBU606, which is a 6 A component), while SilverStone Strider ST50F uses a similar bridge with the same current limit but a higher voltage limit (GBU806). This bridge is more than adequate for a 460 W product: at 115 V this unit would be able to pull only up to 920 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 736 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. This bridge is attached to the same heatsink where the switching transistors are located.
For the active PFC circuit Zalman ZM460-APS uses two SPA20N60C3 transistors, which one capable of delivering up to 20.7 A at 25° C or 13.1 A at 100° C in continuous mode (note the difference temperature makes) or up to 62.1 A in pulse mode. These are the same transistors used by SilverStone Strider ST50F, but Zalman ZM360-APS uses different transistors here, with lower current limits (STP14NK50ZFP: 14 A at 25° C, 7.6 A at 100° C and 48 A at 25° C in pulse mode).
The active PFC capacitor is from CapXon, a Taiwanese company, and rated at 85° C.
In the switching section, two FQPF18N50V2 power MOSFETs are used on the traditional two-transistor forward configuration. Each transistor is capable of delivering up to 18 A at 25° C or 12.1 A at 100° C in continuous mode, or up to 72 A at 25° C in pulse mode. These transistors are different from the ones used Zalman ZM360-APS and SilverStone Strider ST50F: ZM360APS uses two FQPF9N50C (9 A at 25° C, 5.4 A at 100° C and 36 A at 25° C in pulse mode) while SilverStone Strider ST50F uses two STF21NM50N (18 A at 25°, 11 A at 100° C and 72 A at 25° in pulse mode). As you can see while the transistors used on ZM460-APS and ST50F are different, they have similar specs, even though the ones used on ZM460-APS can deliver a little bit more current at 100° C, which is interesting.
The primary is controlled by the omnipresent CM6800 PWM/PFC controller combo.
Now let’s analyze the secondary section from ZM460-APS.
Zalman ZM460-APS uses six Schottky rectifiers on its secondary.
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%. Of course the maximum current (and thus power) this line can really deliver will depend on other components, especially the coil.
The +12 V output is produced by two MBR3060CT Schottky rectifiers in parallel, each one supporting up to 30 A (15 A per internal diode at 125° C). This gives us a maximum theoretical current of 43 A [(15 A x 2)/(1 – 0.30)] or 514 W for the +12 V output. SilverStone Strider ST50F uses different rectifiers, but with the exact same limits. Zalman ZM360-APS uses rectifiers with lower current limits (maximum theoretical current of 29 A and power of 343 W).
The +5 V output is produced by two MBR3045N Schottky rectifiers, supporting up to 30 A at 100° C each (15 A per internal diode). So the maximum theoretical current the +5 V output can deliver is of 43 A or 214 W. These are the exact same components used on both SilverStone Strider ST50F and Zalman ZM360-APS.
The +3.3 V output is produced by another two MBR3045N Schottky rectifiers, supporting up to 30 A at 100° C each (15 A per internal diode). So the maximum theoretical current the +3.3 V output can deliver is of 43 A or 141 W. These are the exact same components used on both SilverStone Strider ST50F and Zalman ZM360-APS.
In Figure 13, you can see the thermal sensor available below the secondary heatsink, in charge of changing the fan speed according to the power supply internal temperature.
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).
The electrolytic capacitors from the secondary are also from CapXon and labeled at 105° C, as usual.
In summary the secondary from this power supply is identical to the secondary from SilverStone Strider ST50F but has a higher current/power limits that the secondary from Zalman ZM360-APS.
In Figure 14, you can see the power supply label containing all the power specs.
This power supply features two +12 V virtual rails distributed like this:
Now let’s see if this power supply can really deliver 460 W.
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 out tests the +12V1 input was connected to the power supply +12V1 (main motherboard cable and peripheral power connectors), while the +12V2 input was connected to the power supply +12V2 rail (ATX12V connector). Thus on this review+12V1 and +12V2 really represent the power supply rails with the same name.
3.5 A (42 W)
7 A (84 W)
10 A (120 W)
13 A (156 W)
16 A (192 W)
3 A (36 W)
6.5 A (78 W)
10 A (120 W)
13 A (156 W)
16 A (192 W)
1 A (5 W)
2 A (10 W)
4 A (20 W)
6 A (30 W)
8 A (40 W)
1 A (3.3 W)
2 A (6.6 W)
4 A (13.2 W)
6 A (19.8 W)
8 A (26.4 W)
1 A (5 W)
1 A (5 W)
1.5 A (7.5 W)
2 A (10 W)
2.5 A (12.5 W)
0.5 A (6 W)
0.5 A (6 W)
0.5 A (6 W)
0.5 A (6 W)
0.8 A (9.6 W)
% Max Load
Ripple and Noise
If you pull up to 80% of this power supply labeled capacity (i.e., up to 368 W) you will have a very good efficiency. At full load efficiency drops, but is still above the 80% mark.
Voltage was always between 3% of their nominal value, which is always good to see, except the -12 V output, which is normal to happen and was still with 5% of its nominal value. ATX specs say that voltages have to be within 5% their nominal values (10% for -12 V).
Ripple and noise level was the highlight from this product. The only problem we saw was that noise level at +12V2 was far higher than at +12V1, but still within specs. See the results below, remembering that the maximum allowed is 50 mV for +5 V and +3.3 V outputs and 120 mV for +12 V outputs. All figures are peak-to-peak values.
Now let’s see if we can pull even more power from Zalman ZM460-APS.
Before overloading power supplies we always test first if the over current protection (OCP) circuit is active and at what level it is configured. For this test we configured our load tester to pull 1 A from each output (0.5 A for -12 V) and increased current at +12V2 until the power supply shut down. This happened when we tried to pull more than 20 A from it. The label says this output has a maximum capacity of 18 A so the OCP from this power supply is configured the way we like: close to what is printed on the power supply label.
Below you can see the maximum values we could pull from this power supply. Far more than that the unit wouldn’t even turn on and if we tried to pull a little bit more current than that (19 A from each +12 V rail) the unit would shut down after one minute. It is always nice to see the power supply protections kicking in. During this overloading noise level was still inside specs and in fact increased just a little bit, to 24 mV at +12V1, +5 V and +3.3 V, with +12V2 at 72.8 mV.
18 A (216 W)
18 A (216 W)
10 A (50 W)
10 A (33 W)
2.5 A (12.5 W)
0.5 A (6 W)
% Max Load
As you can see under this scenario efficiency dropped below the 80% level.
Zalman ZM460-APS power supply specs include:
* Researched at Newegg.com on the day we published this review.
This is a nice power supply for the average user that wants to buy a decent power supply for his or her mainstream PC. ZM460-APS offers very good efficiency (around 85% if you pull between 40% and 60% from the labeled power, i.e., between 184 W and 276 W), which will help you to reduce your electricity bill and has all its protections up and running, meaning you won’t burn it if you try to pull more than it is capable of handling.
Like it happens with other products from this manufacturer, Zalman was conservative when labeling ZM460-APS. It is clearly a 500 W power supply with a 460 W label! In fact internally this power supply is identical to SilverStone Strider ST50F (some components are different but they have exactly the same specs).
But this isn’t a perfect product. There are two main drawbacks. The first one is the limited number of peripheral and SATA power plugs, only four from each. This won’t be a problem for most users but it would be nice if this unit came with six peripheral and six SATA power plugs. The second problem is pricing. It can be found in the US for USD 80, which is not a bad price for a product with this quality, but SilverStone Strider ST50F can be found costing USD 10 less and has six peripheral and six SATA power connectors – and, as mentioned, internally they are the same product. So between the two our recommendation is obvious: buy SilverStone ST50F instead.