Small system builders have a friend in Corsair
Many years ago, I owned a tiny Pentax Auto 110 SLR that looked like a 35mm film camera that had been shrunk in a crazy science experiment.
Opening the box to Corsair’s new SF Series PSU reminded me of the Pentax and how irresistibly cute miniaturised technology can be.
Looking at the pictures, it’s easy to dismiss this design as just another ATX power supply made to the exacting standards of 80 Plus Gold certification with full cable modularisation. But what they don’t convey well is scale. This PSU is just 100mm front to back, 63mm high and 121mm at its widest point. It's specifically designed to be used in SFF cases like those often used for media centres and tiny servers.
Having owned a few of these types of systems, the PSUs that come with them are generally underpowered (300 watts or less), and they often have limited cable support and a fan that kicks in at high RPM from the point you power them up.
Amazingly, all these points are addressed here. The review model offers 450 watts and allocates a healthy 37.5A to the 12V line, with support for a single PCIe 6+2 line.
If that’s insufficient for your needs, Corsair also makes a 600W version, which has dual PCIe lines, bumping the 12V line to 50A.
Both supplies include the correct cabling for ATX12V v2.4 and EPS 2.92 standards and four each of SATA and Molex power connectors.
This connector load-out is as applicable to a full ATX rig as a standard-sized PSU. However, you can’t easily fit into an ATX case, because the mounting holes aren’t correctly spaced.
Corsair considered the possible reuse of the PSU in a full ATX spec design, and for an extra £5.99 it will supply a handy adapter plate.
Cooling is provided by a single 90mm fan that’s thermally controlled by the supply's own sensors. Because of that, it won’t run at all unless the PC it’s connected to is pulling more than 90 watts.
Fan speed scales from 300rpm at a 135W pull to 2010rpm at the full 450 watt load, and it’s a specially designed NR092L PSU fan, not a repurposed case fan. The upshot of that design choice is that you won’t really hear the fan at all on most systems until you use the GPU, and when it does come on, it won’t be intrusive.
Efficiency on this design is also exceptionally good. On 230Vac at 100% load, it’s 92.14% effective, guaranteeing that most of the power makes it to the PC.
The build quality on offer here more than justifies the price. It’s built using the best 105°C rated Japanese capacitors and is superbly engineered throughout.
If I have a criticism it’s that I don’t see the point in the ATX lines being modular, because without them the PSU can’t power up. All connectors are a possible point of failure, above and beyond one that’s permanently soldered. Arguably, though, it could make a tricky SFF case installation easier.
If you’re building a small system, I can’t recommend the Corsair SF Series more highly. Mark Pickavance
A tiny PSU that’s equal to its bigger brothers.