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SilverStone SX650-G PSU Review: Lots Of Power In A Small Form Factor

Our Verdict

If you need an SFX-based PSU with four PCIe connectors and enough power output to handle a couple of high-end graphics cards, then SilverStone's SX650-G is ideal. It doesn't demonstrate ground-breaking performance, but still gets the job done quietly and efficiently.


  • 80 PLUS Gold efficiency helps reduce waste heat
  • Quiet under light and moderate loads
  • Fully modular
  • 4x PCIe connectors
  • FDB fan


  • High price
  • Low efficiency under very light loads
  • Sky-high OPP and OCP on the 3.3V and 5V rails
  • Over-temperature protection doesn't appear functional
  • The fan profile could be tuned better
  • 85°C bulk cap

Features & Specifications

The SX650-G is a small form factor power supply that crams tons of capacity into its SFX chassis. SilverStone has lots of experience building compact, powerful PSUs, and this particular model wields four PCIe connectors able to support two high-end graphics cards. Despite its diminutive dimensions, the SX650-G sports a 92mm fan, which is as large as an SFX enclosure accommodates. This keeps it as quiet as possible under light and moderate loads. Of course, once you really tax the SX650-G, its fan has to spin up to keep the internals cool. At that point, it gets pretty loud.

A three-year warranty is surprisingly short compared to the increasingly long guarantees we're used to seeing. The SX650-G's main competitor, Corsair's SF600, boasts a seven-year warranty. Although that PSU is rated for 50W-lower capacity, it serves up high performance and a semi-passive mode for noise-free operation under light loads. The SF600's most glaring weakness next to the SX650-G are its two PCIe connectors. By doubling that number, SilverStone better caters to enthusiast-oriented hardware configurations.

SilverStone sells a number of SFX-based power supplies: four are fully modular, while three feature fixed cables (but are also more affordable). The SX650-G is one of the modular ones. It's also the most potent model with 80 PLUS Gold and ETA-A efficiency certifications. Inside, you'll find Japanese capacitors exclusively. All of the bundled cables are flat and built with black wires.


Manufacturer (OEM)High Power
Max. DC Output650W
Efficiency80 PLUS Gold, ETA-A (88-91%)
NoiseLAMBDA-S+ (35-40 dB[A])
Modular✓ (Fully)
Intel C6/C7 Power State Support
Operating Temperature (Continuous Full Load)0 - 40°C
Over-Voltage Protection
Under-Voltage Protection
Over-Power Protection
Over-Current (+12V) Protection
Over-Temperature Protection
Short Circuit Protection
Surge Protection
Inrush Current Protection
Fan Failure Protection
No Load Operation
Cooling92mm fluid dynamic bearing Fan (S0921512HB)
Semi-Passive Operation
Dimensions (W x H x D)125 x 63.5 x 100mm
Weight0.923 kg (2.035 lb)
Form FactorATX12V v2.4, EPS 2.92
Warranty3 years

The use of 92mm fans is preferable in the world of SFX PSUs; they facilitate the lowest noise output possible, particularly under demanding loads where thermal output is at its highest. Of course, platform efficiency also plays a major role in the equation, since increased efficiency helps minimize waste heat.

According to SilverStone, the SX650-G includes all of the protection features we'd expect to find. However, we weren't able to trigger over-temperature protection during our tests. Also, over-current protection on the 3.3V rail appears to be set unrealistically high.

Power Specifications

Max. PowerAmps222254.22.50.3
Total Max. Power (W)650

The +12V rail is highly capable; it's able to deliver up to 54A. Meanwhile, the minor rails have ample capacity for any modern PC. The 5VSB rail serves up to 2.5A on paper and more than 4A in practice before over-current protection kicks in.

Cables & Connectors

Modular Cables
DescriptionCable CountConnector Count (Total)GaugeIn Cable Capacitors
ATX connector 20+4 pin (300mm)1116-22AWGNo
4+4 pin EPS12V (410mm)1118AWGNo
6+2 pin PCIe (560mm+150mm)2418AWGNo
SATA (310mm+200mm+100mm)2618AWGNo
Four-pin Molex (300mm+200mm+200mm)1318AWGNo
FDD Adapter (+105mm)1122AWGNo
AC Power Cord (1400mm) - C13 coupler1118AWG-

All of SilverStone's cables are pretty short. After all, this PSU is destined for small cases. There's really no point in buying an SFX-based PSU for a full-tower chassis, and in smaller enclosures the short cables allow for easier routing.

The distance between PCIe connectors is adequate, and it is nice to see a bit of extra space between the first and second SATA connectors. Meanwhile, the four-pin Molex SATA connectors are 20cm away from each other. SilverStone went the extra mile and bundled a Berg adapter for anyone who still needs a FDD connector.

The number of PCIe connectors is sufficient, though it'd be nice if there was a second EPS connector as well, since this PSU has enough power to handle it.

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