SilverStone SFX Series SX700-LPT PSU Review

SilverStone released a powerful new SFX-L unit that boasts 700W capacity, Platinum-rated efficiency, fully modular cabling, and a single +12V rail. The SX700-LPT is based on a Sirfa platform and promises quiet operation thanks to its 120mm fan.

SilverStone has a rich portfolio of SFX-based products that also includes a couple of slightly larger SFX-L units, which are 30 mm deeper. Their major advantage is enough room to accommodate 120mm fans, whereas the standard SFX form factor only has room for 92mm coolers. Of course, the larger the fan the lower the noise; bigger blades can spin more slowly to achieve the same amount of airflow. Moreover, the PCBs inside of SFX-L power supplies usually aren't as cramped, facilitating proper cooling of sensitive components like electrolytic capacitors. It's also easier to achieve higher capacities.

Up until recently, SilverStone only had one SFX-L-based model, the SX500-LG. That changed with the release of its SX700-LPT, though. Aside from higher capacity, the new addition also enables 80 PLUS Platinum-class efficiency.

Like most of SilverStone's SFX PSUs, the SX700-LPT features fully modular cabling, which should make installation a breeze. All filtering caps are provided by a Japanese manufacturer, so besides good performance they also offer increased reliability. A semi-passive feature should keep noise output low under light and moderate loads, too. This mode isn't strictly temperature dependent; it also takes into account how much work the power supply is doing. In our case, we didn't observe any issues. However, combining temperature and load data in order to enable/disable semi-passive operation at the perfect time is challenging. It'd also be nice to have an option for standard fan operation, or at least a way to verify that the fan is working properly. In other semi-passive PSUs that lack a normal fan mode, the fan spins up briefly during start-up. We'd like to see SilverStone implement something similar.

Specifications

At least on paper, the SX700-LPT features a full set of protection capabilities, including over-temperature protection. According to SilverStone, its SX700-LPT can deliver full power for prolonged periods under 40 °C ambient. That looks low considering the ATX spec recommends at least 50 °C. Nonetheless, we will conduct our full load tests in >45 °C as usual, checking to see how well this PSU handles higher temps. Given that OTP is present, heat shouldn't pose an issue.

SilverStone uses a low-speed 120mm fan for cooling. Unfortunately, it sports a sleeve bearing, which doesn't offer the same long lifetime as double ball-bearings or a FDB-based fan. That probably goes a long way in explaining the three-year warranty (though this matches SilverStone's coverage across the SFX portfolio). Only the company's Strider Platinum and Titanium models are covered for five years, along with the ZM1350. We'd like to see SilverStone upgrade its warranty coverage since EVGA, Corsair, and Thermaltake offer up to 10-year protection on their highest-end models.

Power Specifications

Rail3.3V5V12V5VSB-12V
Max. PowerAmps222258.3330.3
Watts120700153.6
Total Max. Power (W)700

The single +12V rail is powerful at 58A, especially considering it's in an SFX-L form factor. This means that two high-end graphics cards could be supported easily. In addition, the minor rails offer a 120W maximum combined power, while the 5VSB rail is a little stronger than expected. With longer cables, the SX700-LPT could be installed in a full-tower chassis and drive a capable gaming machine. As we're about to see, though, the provided cables are very short.

Cables And Connectors

Modular Cables
DescriptionCable CountConnector Count (Total)Gauge
ATX connector 20+4 pin (300mm)1118AWG
4+4 pin EPS12V (400mm)1118AWG
6+2 pin PCIe (550mm+150mm)1218AWG
6+2 pin PCIe (400mm+150mm)1218AWG
SATA (300mm+200mm+100mm)2618AWG
SATA (610mm+150mm+150mm)1318AWG
Four-pin Molex (300mm+200mm+100mm)1318AWG
FDD Adapter (+100mm)1122AWG

The SX700-LPT has an adequate number of connectors for its capacity. However, the 24-pin ATX cable is too short, so you're only able to install this PSU in small enclosures. The EPS cable is short as well, though not as short as the main ATX cable. It'd be interesting if there were two versions of the SX700-LPT, one with these short cables, and another sporting longer cables and an SFX-to-ATX adapter. That'd let you pick the model best suited to your case.

The distance between connectors is ample, and the provided Berg connector thankfully comes in adapter form (instead of being fixed onto one of the peripheral cables). Finally, all connectors except the FDD one use 18-gauge wires.

Power Distribution

Since this PSU features a single +12V rail, we do not have anything to say about its power distribution.

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