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[nextpage title=”Introduction”]

FSP300-60GHS is a small 300 W SFX power supply from FSP targeted to small form factor (SFF) PCs. It measures only 5” x 4” x 2.5” (12.5 x 10 x 6.2 cm), while standard ATX power supplies measure at least 6” x 5 ½” x 3 ¼” (15 x 14 x 8.5 cm). The unit we reviewed came inside SilverStone Sugo SG05 SFF case. Let’s see whether this is a good power supply or not.

Our contact at SilverStone sent us an e-mail explaining that this power supply we reviewed and that comes inside SG05 is a little bit different from the standard FSP300-60GHS:

• Lower acoustics across all loading conditions
• SilverStone specific cable definition (type and length)
• Different +12V distribution through connectors to better support medium high-end graphics cards

Figure 1: FSP300-60GHS power supply.

Figure 2: FSP300-60GHS power supply.

Because its reduced side, it uses a slim 80 mm fan on its bottom. FSP300-60GHS features active PFC, allowing FSP to market it in Europe.

The cables have no nylon protection, and the included cables are:

• Main motherboard cable with a 20/24-pin connector.
• One cable with one ATX12V connector.
• One auxiliary power cable for video cards with one six-pin connector.
• One SATA power cable with three SATA power connectors.
• One peripheral power cable with two standard peripheral power connectors and one floppy disk drive power connector.

The number of cables is more than enough for building a small form factor (SFF) PC.

All wires are 18 AWG, which is the correct gauge to be used. The ATX12V and the video card cables measure 15 ¾” (40 cm), while all other cables measure 12” (30 cm) between the power supply and the first connector on the cable. On the SATA power cables there is 7 3/4” (19.5 cm) between the first and the second connectors, but only 4” (10 cm) between the second and the third connectors. On the peripheral power cable there is 7 ½” (19 cm) between each connector.

Figure 3: Cables.

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

[nextpage title=”A Look Inside The FSP300-60GHS”]

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.

Figure 4: Overall look.

Figure 5: Overall look.

Figure 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.

The transient filtering stage from this power supply is flawless, providing one X capacitor, two Y capacitors and two ferrite coils more than required. This is really nice to see, especially on a low-wattage product.

Figure 7: Transient filtering stage (part 1).

Figure 8: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion about the components used in the FSP300-60GHS.[nextpage title=”Primary Analysis”]

On this page we will take an in-depth look at the primary stage of FSP300-60GHS. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBU605 rectifying bridge in its primary, which can deliver up to 6 A at 100° C. This component is clearly overspec’ed: 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.

Figure 9: Rectifying bridge.

On the active PFC circuit one FDPF18N50 power MOSFET transistors is used, capable of delivering up to 18 A at 25° C or 10.8 A at 100° C in continuous mode (note the difference temperature makes), or up to 72 A in pulse mode at 25° C. This transistor presents a resistance of 265 mΩ when turned on, a characteristic called RDS(on). This number indicates the amount of power that is wasted, so the lower this number the better, as less power will be wasted thus increasing efficiency. As you can see this power supply uses only one transistor instead of two, which is more common. This was done probably to reduce the size of the unit.

Figure 10: Active PFC diode and transistor.

This power supply uses a Teapo capacitor labeled at 105° C to filter the output from the active PFC circuit. It is always good to see power supplies using capacitors labeled at 105° C instead of 85° C here.

In the switching section, two FQPF9N50C power MOSFET transistors are used on the traditional two-transistor forward configuration. Each one is capable of delivering up to 9 A at 25° C or 5.4 A at 100° C in continuous mode (note the difference temperature makes), or up to 36 A in pulse mode at 25° C. These transistors present an RDS(on) of 800 mΩ (too high in our opinion).

Figure 11: Switching transistors.

The primary is controlled by a PFC/PWM combo controller from Champion Micro, but we couldn’t read the exact model.

Figure 12: PFC/PWM combo controller.

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

[nextpage title=”Secondary Analysis”]

This power supply uses three Schottky rectifiers on its secondary, one for each main positive output (+12 V, +5 V and +3.3 V), and they are all from the same model: SBR30A50CT (30 A, 15 A per internal diode at 110° C, maximum voltage drop of 0.55 V).

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%.

This gives a maximum theoretical current of 21 A for each line. This translates into 257 W for the +12 V output, 107 W for the +5 V output and 71 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.

Figure 13: Rectifiers.

The secondary is monitored by a PS229 integrated circuit. Unfortunately this device isn’t listed o its manufacturer website, so we can’t tell which protection it really supports.

Figure 14: Monitoring integrated circuit.

All electrolytic capacitors from the secondary are also from Teapo and labeled at 105° C, as usual.

[nextpage title=”Power Distribution”]

In Figure 15, you can see the power supply label containing all the power specs.

Figure 15: Power supply label.

This power supply uses a dual-rail design, and the rails are distributed like this:

• +12V1 (solid yellow wire): All cables but the video card auxiliary power cable.
• +12V2 (yellow with black stripe wire): Video card auxiliary power cable.

This is the best distribution, in our opinion, as the CPU and the video card are located on separated rails.

Now let’s see if this power supply can really deliver 300 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.

+12V1 and +12V2 are the two independent +12V inputs from our load tester and during our tests the +12V1 input was connected to the power supply +12V1 and +12V2 rails and the +12V2 input was connected to the power supply +12V1 rail (ATX12V connector).

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12V1	2 A (24 W)	4 A (48 W)	6 A (72 W)	8 A (96 W)	10.5 A (126 W)
+12V2	1.5 A (18 W)	3.5 A (42 W)	6 A (72 W)	8 A (96 W)	10 A (120 W)
+5V	1 A (5 W)	2 A (10 W)	3 A (15 W)	4 A (20 W)	5 A (25 W)
+3.3 V	1 A (3.3 W)	2 A (6.6 W)	3 A (9.9 W)	4 A (13.2 W)	5 A (16.5 W)
+5VSB	1 A (5 W)	1 A (5 W)	1.5 A (7.5 W)	2 A (10 W0	2 A (10 W0
-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	60.4 W	115.9 W	179.2 W	236.3 W	296.0 W
% Max Load	20.1%	38.6%	59.7%	78.8%	98.7%
Room Temp.	39.0° C	38.2° C	38.6° C	39.3° C	39.8° C
PSU Temp.	42.8° C	44.2° C	43.5° C	39.7° C	46.0° C
Voltage Stability	Pass	Pass	Pass	Pass	Fail on +5VSB
Ripple and Noise	Pass	Pass	Pass	Pass	Pass
AC Power	74.4 W	138.0 W	212.3 W	283.7 W	363.5 W
Efficiency	81.2%	84.0%	84.4%	83.3%	81.4%
AC Voltage	115.7 V	115.1 V	114.2 V	113.4 V	112.9 V
Power Factor	0.993	0.986	0.987	0.988	0.989
Final Result	Pass	Pass	Pass	Pass	Pass

We had to be more generous with temperature while reviewing this power supply. We usually wait until the temperature inside our thermal chamber is between 45° C and 50° C to start collecting data, however since this is a low wattage unit, temperature delayed a lot to increase and the maximum we could get was 39° C.

FSP300-60GHS presents a very good efficiency around 83%-84% when you pull between 40% and 80% from its labeled capacity (i.e., between 120 W and 240 W). At light load (20% load, i.e., 60 W) and full load (300 W) efficiency dropped, but was still above 81%, what is good.

The main outputs (+12 V, +5 V and +3.3 V) were always within 3% from their nominal value, whereas the ATX specification says they must be within 5%. Translation: voltages were closer to their nominal values than needed. The standby voltage (+5VSB), however, touched the 4.75 V limit during test number four and dropped below it (4.72 V) during test number five.

Ripple and noise were low. You can see the results for test number five below. All numbers are peak-to-peak figures and the maximum allowed is 120 mV for the +12 V outputs and 50 mV for the +3.3 V and +5 V outputs.

Figure 16: +12V1 input from load tester at 296.0 W (59 mV).

Figure 17: +12V2 input from load tester at 296.0 W (65.2 mV).

Figure 18: +5V rail with power supply delivering 296.0 W (29.8 mV).

Figure 19: +3.3 V rail with power supply delivering 296.0 W (17.8 mV).

Let’s see if we could pull more than 300 W from this unit.

[nextpage title=”Overload Tests”]

Before overloading a power supply we always test to see if over current protection (OCP) is active and at what current level it is triggered. To test this, we connected all cables that were connected to the power supply +12V1 rail to the load tester +12V1 input and started increasing current until the power supply would shut down. This happened when we tried to pull 22 A or more from it, meaning that OCP on +12V1 rail is configured at this value.

Then starting from test five we increased currents to the maximum we could with the power supply still running inside ATX specs. If we tried to increase one amp ripple would go to the roof, meaning that the unit stopped working correctly. Also after more or less 30 seconds running on this configuration the same thing happened, meaning that the maximum we could extract was only “peak power” and not “continuous power.”

The idea behind of overload tests is to see if the power supply will burn/explode and see if the protections from the power supply are working correctly. This power supply didn’t burn and when we tried to pull far more than it could deliver it would shut down, so this unit passed on this test.

Input	Maximum
+12V1	13 A (156 W)
+12V2	13 A (156 W)
+5V	5 A (25 W)
+3.3 V	5 A (16.5 W)
+5VSB	2 A (10 W)
-12 V	0.5 A (6 W)
Total	358.3 W
% Max Load	119.4%
Room Temp.	39.1° C
PSU Temp.	47.6° C
AC Power	451.6 W
Efficiency	79.3%
AC Voltage	111.6 V
Power Factor	0.989

[nextpage title=”Main Specifications”]

FSP300-60GHS power supply specs include:

• SFX12V
• Nominal labeled power: 300 W.
• Measured maximum power: 358.3 W at 39.1° C.
• Labeled efficiency: 80% minimum (80 Plus certified).
• Measured efficiency: Between 81.2% and 84.4% at 115 V (nominal, see complete results for actual voltage).
• Active PFC: Yes.
• Modular Cabling System: No.
• Motherboard Power Connectors: One 20/24-pin connector and one ATX12V connector.
• Video Card Power Connectors: One six-pin connector.
• Peripheral Power Connectors: Two in one cable.
• Floppy Disk Drive Power Connectors: One.
• SATA Power Connectors: Three in one cable.
• Protections: Over voltage (OVP, not tested), over current (OCP, tested and working) and short-circuit (SCP, tested and working).
• Warranty: Information not available.
• More Information: https://www.fsp-group.com
• Average price in the US: We couldn’t find this product being sold in the US market on the day we published this review.

[nextpage title=”Conclusions”]

FSP300-60GHS performed well during our tests, presenting high efficiency up to 84.4% and really being able to deliver 300 W.

This is certainly a good option for people building small computers based on the SFX standard.

SilverStone Sugo SG05 comes with it and it seems to be a good match.