The FSP Twins 500 W piqued my interest, this being the first time I have had to deal with a hybrid server/desktop PSU. Its implementation is interesting, without a doubt, but it could be better with several modifications. For instance, for a server-like PSU, special modules are required, capable of providing the minor rails as well. However, such an approach would have been expensive since FSP would have had to design a special power module and manufacture it as well. Instead of doing so and in order to keep the price as low as possible - although $400 is still very stiff - FSP decided to go with normal server modules, which don't output 5V and 3.3V, but, instead, only produce +12V and 5VSB. To generate the minor rails, the unit's frame had to house their regulation circuits, and since the minor rails have a combined maximum power of 130 W, both power modules have to operate in parallel to meet the demands of all the rails. This does in a way affects the PSU's reliability since there is still a slight chance for both modules to fail at the same time due to them having run similar operating hours. The ideal solution would be for only one to operate while the other is in standby, ready to take over should the other fail. This would fix the PSU's poor efficiency as well, especially at light loads.

Another major problem with the Twins 500 W is its excessive noise output regardless of its operating conditions. Given that it features a digital interface, a way to adjust its fan profile to quieten it down would have been nice, at least under light loads. FSP should look into this matter because their Twins PSU is most likely not going to make it into a server PC its user will isolate physically; it will, rather, be for a normal PC inside a home or an office. It is great to have the redundancy feature along with ATX compatibility, but with such high noise output, I seriously doubt many will go for FSP's offer.

This is the first PSU of its kind, so some things are naturally in need a redesign, or a different approach. But this is a start, and I hope FSP will continue working on this project by introducing an improved version and not just a higher capacity model to market (by the way, the FSP Twins 700 W is on its way). Modular cables and more PCIe and SATA connectors would be highly welcome as well. As for the stiff price, I don't believe much can be done about it since server-type PSUs just are very expensive.