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[nextpage title=”Introduction”]

Let’s take a look at this entry-level 650 W power supply from Seventeam that carries the 80 Plus Bronze certification.

Seventeam ST-650PWL power supplyFigure 1: Seventeam ST-650PWL power supply

Seventeam ST-650PWL power supplyFigure 2: Seventeam ST-650PWL power supply

The Seventeam ST-650PWL is 5.5” (140 mm) deep, with a 120 mm dual ball bearing fan (Protechnic Magic MGA12012XB-025) on its bottom part.

The reviewed unit doesn’t have a modular cabling system, and the cables don’t have nylon sleeves. The power supply comes with the following cables:

  • Main motherboard cable with a 20/24-pin connector, 16.1” (41 cm) long
  • One cable with two ATX12V connectors that together form an EPS12V connector, 20” (51 cm) long
  • Two cables with one six/eight-pin connector for video cards each, 16.5” (42 cm) long
  • Two cables with three SATA power connectors each, 14.2” (36 cm) to the first connector, 5.9” (15 cm) between connectors
  • One cable with three standard peripheral power connectors and one floppy disk drive power connector, 14.2” (36 cm) to the first connector, 5.9” (15 cm) between connectors

All wires are 18 AWG, which is the minimum recommended gauge, except the +3.3 V (orange) and +5 V (red) wires on the main motherboard cable, which are thicker (16 AWG), which is always nice to see.

The number of cables and connectors is compatible with an entry-level 650 W unit. We’d prefer to see four video card cables, which would allow you to install two high-end video cards at the same time without the need for adapters. The reduced number of peripheral power connectors may be a problem.

Seventeam ST-650PWL power supplyFigure 3: Cables

Let’s now take an in-depth look inside this power supply.

[nextpage title=”A Look Inside The Seventeam ST-650PWL”]

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.

Seventeam ST-650PWL power supplyFigure 4: Top view

Seventeam ST-650PWL power supplyFigure 5: Front quarter view

Seventeam ST-650PWL power supplyFigure 6: Rear quarter view

Seventeam ST-650PWL power supplyFigure 7: Printed circuit board

[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 of the Seventeam ST-650PWL is impeccable, coming with all required components plus one extra X capacitor, two extra Y capacitors, and one extra ferrite coil.

Seventeam ST-650PWL power supplyFigure 8: Transient filtering stage (part 1)

Seventeam ST-650PWL power supplyFigure 9: Transient filtering stage (part 2)

In the next page we will have a more detailed discussion about the components used in the Seventeam ST-650PWL.

[nextpage title=”Primary Analysis”]

On this page we will take an in-depth look at the primary stage of the Seventeam ST-650PWL. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU1008 rectifying bridges connected in parallel, attached to the same heatsink as the active PFC and switching transistors. Each bridge supports up to 10 A at 100° C so, in theory, you would be able to pull up to 2,300 W from a 115 V power grid. Assuming 80% efficiency, the bridges would allow this unit to deliver up to 1,840 W without burning themselves out. Of course, we are only talking about these components, and the real limit will depend on all the other components in this power supply.

Seventeam ST-650PWL power supplyFigure 10: Rectifying bridges

The active PFC circuit uses two SPW35N60C3 MOSFETs, which are capable of delivering up to 34.6 A at 25° C or up to 21.9 A at 100° C (note the difference temperature makes) in continuous mode, or up to 103.8 A in pulse mode at 25° C, each. These transistors present a 100 mΩ resistance when turned on, a characteristic called RDS(on). The lower this number the better, meaning that the transistors will waste less power a
nd the power supply will achieve higher efficiency.

The output of the active PFC circuit is filtered by a capacitor from Su’scon, labeled at 85° C.

In the switching section, two SPP24N60C3 MOSFET transistors are used, installed in the two-transistor forward configuration. Each one supports up to 24.3 A at 25° C or up to 15.4 A at 100° C in continuous mode, or up to 72.9 A at 25° C in pulse mode, with a 160 mΩ RDS(on).

Seventeam ST-650PWL power supplyFigure 11: Switching and active PFC transistors

The primary is controlled by the famous CM6800 active PFC/PWM combo controller.

Seventeam ST-650PWL power supplyFigure 12: Active PFC/PWM combo controller

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

[nextpage title=”Secondary Analysis”]

This power supply has eight Schottky rectifiers on its secondary heatsink, all the same model: PFR30V45CT. Each one supports up to 30 A (15 A per internal diode at 120° C, 0.45 V maximum voltage drop).

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. As an exercise, we can assume a duty cycle of 30%.

The +12 V output uses four of those rectifiers, giving us a maximum theoretical current of 86 A or 1,029 W for the +12 V output.

The +5 V output uses two of those rectifiers, giving us a maximum theoretical current of 43 A or 214 W for the +5 V output.

The +3.3 V output uses the other two rectifiers, giving us a maximum theoretical current of 43 A or 141 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.

Seventeam ST-650PWL power supplyFigure 13: +3.3 V, +5 V and +12 V rectifiers

The secondary is monitored by a PS113 integrated circuit, which supports only over voltage (OVP) and  under voltage (UVP) protections.

Seventeam ST-650PWL power supplyFigure 14: Monitoring circuit

All electrolytic capacitors used in this power supply are also from Su’scon and labeled at 105° C.

[nextpage title=”Power Distribution”]

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

Seventeam ST-650PWL power supplyFigure 15: Power supply label

As you can see, according to the label this unit has two +12 V rails, but this is a lie. Inside the unit all +12 V wires are connected to the same spot on the printed circuit board, plus this unit doesn’t have over current protection, which is required for building multi-rail power supplies (click here to understand). Therefore, this unit has a single-rail design.

Let’s now see if this power supply can really deliver 650 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 the behavior of the reviewed unit 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 powers listed for each test, you may find a different value than what is posted under “Total” below. Since each output can have a slight variation (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. In the “Total” row, we are using the real amount of power being delivered, as measured by our load tester.

The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During our tests, the +12VA and +12VB input were connected to the power supply single +12 V rail (the EPS12V connector was installed on the +12VB input of our load tester).

Input Test 1 Test 2 Test 3 Test 4 Test 5
+12VA 5 A (60 W) 10 A (120 W) 15 A (180 W) 20 A (240 W) 23.75 A (285 W)
+12VB 5 A (60 W) 10 A (120 W) 15 A (180 W) 20 A (240 W) 23.75 A (285 W)
+5V 1 A (5 W) 2 A (10 W) 4 A (20 W) 6 A (30 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) 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)
-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 142.0 W 271.8 W 400.2 W 548.6 W 655.8 W
% Max Load 21.8% 41.8% 61.6% 84.4% 100.9%
Room Temp. 46.8° C 45.9° C 47.2° C 45.2° C 48.8° C
PSU Temp. 46.6° C 48.0° C 48.7° C 47.6° C 50.5° C
Voltage Regulation Pass Pass Pass Pass Pass
Ripple and Noise Pass Pass Pass Pass Pass
AC Power 172.6 W 320.5 W 473.6 W 664.0 W 812.0 W
Efficiency 82.3% 84.8% 84.5% 82.6% 80.8%
AC Voltage 115.2 V 113.3 V 111.5 V 109.2 V 107.5 V
Power Factor 0.971 0.984

0.991 0.994 0.996
Final Result Pass Pass Pass Pass Pass

The Seventeam ST-650PWL can really deliver its labeled wattage at high temperatures.

Efficiency was good, between 80.8% and 84.5%. This unit has the 80 Plus Bronze certification, meaning that it should be able to present at least 82% efficiency at light (20%) and full loads, and at least 85% efficiency at typical (50%) load. During our tests, however, this unit had 80.8% efficiency at full load. We see this happening all the time, since Ecos Consulting (the company behind the 80 Plus certification) tests power supplies at only 23° C, and we tested this particular unit between 45° C and 49° C, and efficiency drops with temperature.

Voltages were always inside their proper range (5% for the positive voltages and 10% for the -12 V output). During our tests the +12 V, +3.3 V and +5VSB outputs were closer to their nominal values than necessary (3% regulation), but we didn’t see the same happening with the +5 V and -12 V outputs, but they were still inside the allowed range.

Noise and ripple levels were low, except the +3.3 V and +5VSB outputs during test five. The 3.3 V presented a high level of noise and ripple, but they were still below the maximum allowed. The noise and ripple levels at +5VSB output, however, was exactly at 50 mV, which is the maximum allowed. Below you can see the results for the power supply outputs during test number five. The maximum allowed is 120 mV for the +12 V and -12 V outputs, and 50 mV for the +5 V, +3.3 V, and +5VSB outputs. All values are peak-to-peak figures.

Seventeam ST-650PWL power supplyFigure 16: +12VA input from load tester during test five at 655.8 W (30.4 mV)

Seventeam ST-650PWL power supplyFigure 17: +12VB input from load tester during test five at 655.8 W (31.2 mV)

Seventeam ST-650PWL power supplyFigure 18: +5V rail during test five at 655.8 W (31.2 mV)

Seventeam ST-650PWL power supplyFigure 19: +3.3 V rail during test five at 655.8 W (42.2 mV)

Let’s see if we can pull even more from the Seventeam ST-650PWL.

[nextpage title=”Overload Tests”]

Below you can see the maximum we could pull from this power supply. We couldn’t pull more than that because the power supply shut down, showing that its protections are working just fine. During this test the noise and ripple levels at +5VSB were above the maximum allowed, at 61.2 mV, and the noise and ripple levels at +3.3 V were touching the limit, at 48.6 mV. The voltage at +5 V output was below the minimum allowed, at +4.71 V.

Input Overload Test
+12VA 26 A (312 W)
+12VB 26 A (312 W)
+5V 10 A (50 W)
+3.3 V 10 A (33 W)
+5VSB 2.5 A (12.5 W)
-12 V 0.5 A (6 W)
Total 718 W
% Max Load 110.5%
Room Temp. 47.4° C
PSU Temp. 48.6° C
AC Power 902 W
Efficiency 79.6%
AC Voltage 106.8 V
Power Factor 0.997

[nextpage title=”Main Specifications”]

The specs of the Seventeam ST-650PWL include:

  • Standards: ATX12V 2.3
  • Nominal labeled power: 650 W
  • Measured maximum power: 718 W at 47.4° C ambient
  • Labeled efficiency: 82% minimum, 80 Plus Bronze certification
  • Measured efficiency: Between 80.8% and 84.8% 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 two ATX12V connectors that together form an EPS12V connector
  • Video Card Power Connectors: Two six/eight-pint connectors on separate cables
  • SATA Power Connectors: Six on two cables
  • Peripheral Power Connectors: Three on one cable
  • Floppy Disk Drive Power Connectors: One
  • Protections (as listed by the manufacturer): Over power (OPP), over voltage (OVP), under voltage (UVP), over temperature (OTP), and short-circuit (SCP)
  • Are the above protections really available? Yes
  • Warranty: NA
  • More Information: https://www.seventeam.com.tw
  • Average Price in the US: We couldn’t find this power supply being sold in the US on the day we published this review

[nextpage title=”Conclusions”]

The Seventeam ST-650PWL is clearly an entry-level 650 W power supply, bringing a relatively reduced number of cables and connectors when compared to more expensive 650 W models. It can really deliver its labeled power at high temperatures, has very good efficiency for its category, voltages within the proper range, and noise and ripple levels below the maximum allowed.

The ST-650PWL is a good option for users that want an affordable 650 W power supply with decent efficiency and that won’t fry the components of their PC. In fact, the ST-650PWL is a better option than the ST-650P-AF from the same manufacturer, due to its higher efficiency.

By the way, the Cooler Master GX 650 W power supply is a relabeled Seventeam ST-650PWL.