SilverStone SX500-LG Power Supply Review

SilverStone's SX500-LG fits into the new SFX-L form factor. It's longer than normal SFX units, allowing for a larger fan that reduces output noise.

SilverStone is a key player in the SFX PSU space, with several offerings in that category. Unfortunately, the form factor's shallow depth doesn't allow for fans larger than 80mm in diameter. And smaller fans mean more noise output, since they have to spin faster.

Because acoustics are an important buying factor for many users nowadays, SilverStone tweaked the SFX form factor and introduced SFX-L, which has the same width and height as SFX, but specifies increased depth to allow for a larger cooling fan that's up to 120mm in diameter.

If you look at the top of the newly released SX500-LG PSU, you will notice that the fan covers most of it. SilverStone used the largest fan that'd fit, which in this case has a 120mm diameter. The difference in noise between an 80 and 120mm fan providing the same airflow can be tremendous, especially at higher loads and under tough conditions. Thus, we think SilverStone made the right move with its SFX-L form factor, and we hope the series will follow with additional units in the future. In addition to less noise at high loads, the SX500-LG also generates a lower-pitch tone compared to its smaller SFX-based siblings using 80mm fans.


The SX500-LG PSU meets the 80 PLUS Gold requirements, which should allow for a more relaxed fan profile, since energy loss will be kept at low levels even under full-load conditions. Thus, the fan won't have to rotate at its maximum speed in order to dissipate heat. In addition, the SX500-LG features a semi-passive mode, so at light loads it's totally inaudible. This is good news for the sleeve-bearing fan since it translates to a longer lifespan. That's a crucial point; fans with this bearing type don't last as long as those using fluid dynamic ball bearings (FDB).

Like most SilverStone units, this is a fully modular PSU featuring all protections except for OTP (over-temperature protection), according to the company's official specs. That's not good, since the highest operating temperature this unit can deliver its full load continuously is restricted to only 40 degrees Celsius, while the ATX spec recommends 50 degrees. During our breakdown process, however, we discovered that the SX500-LG's supervisor IC does support OTP. We also found two thermistors attached to the secondary heat sink, which means OTP must be present with a trigger point higher than 46 degrees Celsius (after all, we didn't encounter any unexpected shutdowns during our hot-box test sessions).

In the dimensions section, we see that the only difference between the SFX-L and SFX units is a 13cm depth measurement compared to 10cm, respectively. The warranty on the SX500-LG PSUs is respectable at three years, though we'd prefer even longer coverage. The PSU is priced at $100, which doesn't make it inexpensive. However, compact dimensions can significantly increase PSU production costs, affecting the final retail price.

Power Specifications

Max. PowerAmps20204030.3
Watts          105480153.6
Total Max. Power (W)


The single +12V rail in the SX500-LG can deliver up to 40A, meaning it can easily handle two mid-range graphics card or one higher-end model. The minor rails have a rather unusual max combined power level, which barely exceeds 100W, so it will suffice for all systems that are covered by a 500W PSU. Finally, the 5VSB rail is a bit more powerful than usual, making it a very welcome feature.

Cables And Connectors

Modular Cables 
  ATX connector (300mm)20+4 pin
  4+4 pin EPS12V (410mm)1
  6+2 pin PCIe (405mm+150mm)2
  SATA (300mm+200mm+100mm)3
  Four-pin Molex (300mm+200mm) / FDD (+200mm)2 / 1

All cables are short, since this PSU is designed for smaller enclosures. Longer cables would only cause trouble for routing and management. The distance among connectors is pretty long, which can prove to be helpful, even in small cases. The only downside is the low number of SATA connectors, which should be at least six based on this unit's capacity, not three. Some users might ask for more PCIe connectivity, which is understandable since even a compact PSU could handle two mid-range cards. However, we aren't sure if a small chassis, which this PSU is intended for, is even meant for such a configuration. Finally, all connectors use 18AWG wires, which are typical in most PSUs nowadays.

Power Distribution

Since this PSU features a single +12V rail, there's nothing to say about its power distribution.