Corsair SF1000 ATX v3.1 PSU Review – Small power dwarf for thirsty ITX builds

1 - Introduction and technical data 2 - Unboxing, cables and protection circuits 3 - Teardown: Topology and components 4 - Load Regulation, Ripple Suppression 5 - Transient Response 6 - Hold-Up Time, Timings, Inrush-Current 7 - Average Efficiency and PF 8 - Noise and fan control 9 - Summary and conclusion

Topology and teardown

Great Wall is the original equipment manufacturer for all SF and SF-L devices. It is a Chinese state-owned enterprise, so it has abundant resources. The PCB is small and densely populated with components that deliver a maximum power of 1000W. The primary heat sink, which houses the bridge rectifiers among other components, is quite large, while the heat sink on the secondary side is small, as the FETs that regulate the 12V rail are installed on the bottom of the board. Overall, the build quality is high, with expensive components and near-impeccable soldering quality. Great Wall has state of the art production lines, so I expected nothing less when it came to soldering quality. I had the opportunity to visit all of GW’s factories and production lines in 2023, and production of the new SF line was taking place at the time of my visit.

01 top1-2

02 top2-2

03 top3-2

04 top4-2

05 transient1-2

06 transienta1-2

07 transienta2-2

08 transientb2-2

09 MOV-2

10 NTC__relay-2

11 bridge_rectifiers1-2

12 bridge_rectifiers2-2

13 APFC_side

14 APFC_Fets1-1

15 boost_diode-1

16 main_FETs-1

17 resonant_controller-1

18 main_transformer-1

19 12v_FETs-1

20 minor_rail_board-1

21 minor_rail_FETs

22 caps1-1

23 caps2-1

24 caps3-1

25 caps4-1

26 caps5

27 driver_IC-1

28 supervisor_IC-1

29 modular_front1-1

30 modular_front2-1

31 modular_front3-1

32 5vsb_rectifier-1

33 5vsb_rectifier__5vsb_controller-1

34 5vsb_transformer-1

35 main_PCB1-1

36 main_PCB2-1

37 main_PCB3-1

38 fan_controler__VRMS-1

39 Fan-1

40 fan_close-1

The design can be found in every modern power supply today. A half-bridge topology on the primary side, after the APFC converter stage, while an LLC resonant converter increases efficiency through (almost) lossless switching. On the secondary side, a synchronous rectifier circuit with eight (instead of six as in the 850W) Infineon FETs regulates the 12-volt rail. The secondary rails are generated by two DC-DC converters that use an ANPEC PWM controller. Rubycon supplies the few electrolytic caps on the secondary side, while many polymer caps provide the ripple filtering. The fan is controlled by a digital microchip controller, which facilitates the programming of the fan speed profile. The fan uses a fluid dynamic bearing and has a diameter of 92 mm. Finally, the standby circuit uses Infineon components.

Great Wall has gained extensive experience over the years by working with Corsair in the manufacture of SFX devices and is therefore now number one in this market segment.

Component overview

Finally, I have listed all the components used for interested readers: