The SilverStone SX1000 is the most powerful small unit we've ever tested, with enough connectors to support a powerful gaming system. This is why it was our top choice in our guide to the best power supplies for gaming in this category (open in new tab).

Best of all, its noise output is not noticeable at loads below 700W, unless you are super-sensitive.

The SX1000 will empty your wallet, especially in the IT world, where everything small and powerful is usually expensive. Nevertheless, PSUs are inexpensive, given the important role they play in any system. Not long ago, you were paying $1000+ to get a mid-level graphics card, so a $250-$300 power supply doesn't seem that expensive, especially considering you'll be using it for years.

SilverStone's SX PSU line consists of two SFX-L units with capacities of 750W and 1000W; the SX1000 has a power density of 969W/liter, the highest level we've seen.

SilverStone has equipped it with two EPS and six PCIe connectors to provide full power without problems. In addition, all cables are modular, facilitating PSU installation; due to the small size of the PCB, internal temperatures can be high, so double ball bearing fans are used which can handle high temperature conditions without problems. In general, DBB fans are considered higher quality than FDB fans, but they are more expensive, so the latter dominate the high-end market.

Despite the high power density, the platform design is clean: OEM Enhance Electronics uses large heat sinks on the primary side, and the APFC heat sinks are perforated to allow airflow to flow to the components installed beneath them The APFC heat sinks are perforated to allow airflow to the components installed underneath. Since there was no space on the small PCB for one large main transformer, Enhance Electronics installed two smaller transformers in parallel. The primary and secondary filter caps are of high quality, as are the 120mm diameter Globe Fan DBB fans.

One notable advantage of the SFX-L form factor is that it allows up to 120mm fans and low noise output, whereas SFX units are limited to 92mm fans in the best case scenario.

The 12V rail can supply the full power of the PSU, and the minor rails together can support up to 125W.

With two EPS and six PCIe connectors, the PSU has no problem delivering full power; there is no 12+4 PCIe connector, but we expect SilverStone to update this platform soon. The cables are short as this PSU is for a small chassis, but SilverStone should offer longer cable versions, including an SFX-to-ATX adapter.

Load regulation is tight enough at 12V, but not so tight at the minor rails. Ripple suppression could also be better at 12V. More filtering caps would be needed to reduce ripple on this rail, but the PCB is not large enough to accommodate them. In-cable capacitors would improve performance in this area; with better ripple suppression at 12V, the SX1000 could easily achieve the highest point for any PSU.

Hold-up time exceeds 17 ms, which is not easy to achieve for high power density PSUs due to limited space to install bulk caps of sufficient size. Inrush currents are at normal levels, though.

Efficiency is high at normal and very light loads, but could be higher at light loads. 5VSB rails also achieve the highest efficiency scores. Bumper power is low at 115V, but should be below 0.1W at 230V input.

Transient response at 12V is among the best we have seen so far in this form factor category, and is even with many normal dimension PSUs of similar capacity. Other rails also have good transient response.

It is surprising that the SFX-L PSU delivers nearly 1500W. Nevertheless, it would be safer if the +12V OCP and OPP trigger points were set more modestly, around 130%. Finally, there is over-temperature protection, and the other protective functions are working fine.

The average noise output is higher than 35 dBA, as fan noise increases at high loads. It is very difficult, if not impossible, for such a high power density PSU to remain quiet under heavy load.

The SX1000 is the most powerful small form factor PSU on the market today, and is much more powerful than its paper specs because it actually drives close to 1500W. The main replacement for this PSU is the Corsair SF750, but we would still choose the SilverStone in a pinch.

Enhance is that the OEM behind this platform provided SilverStone with a solid unit with good build quality and top-notch parts. The only drawback is that the small PCB does not allow for many filtering caps to be installed and the ripple at 12V is not very large; SilverStone should probably use in-cable caps to enhance ripple suppression. This type of cable is not preferred by most users because it is more difficult to install, but it is cheaper, in our opinion, because the ripple is lower, which plays an important role in system reliability and longevity.