Seasonic SS-300M1U and SS-350M1U
These PSUs are designed for mini 1U servers as is indicated by their model names. However, they are also compatible with the FlexATX standard (namely, Low-profile Power Supply #2).
Recalling compact computer cases we tested, the Cooler Master Elite 100 won't accommodate a PSU of that length (the HDD rack will get in the way): a shorter PSU is needed, even though the mounting holes coincide. Such short PSUs are available too, although are not described in the FlexATX specs. As a matter of fact, Seasonic markets its shorter models (with a length of 150 mm) as FlexATX whereas its 190mm-long PSUs are positioned as ATX12V v2.31/EPS12V.
There are computer cases like the Delux DLC-MS126 which come with 190mm PSUs. So, one of these Seasonic models can be used to replace the Delux’s bundled PSU (which is reported to be very noisy).
These PSUs, like the rest of products covered in this review, came to us without any packaging, so we won’t be able to describe their accessories. Let's get right to the PSUs themselves.
It’s hard to invent anything extraordinary in terms of exterior design when it comes to this form-factor. The rear end of this PSU may only be different from same-class products in the shape of the punched-out grid over the 40mm fan.
The other end of the case is somewhat more original. The power cables are detachable, which is unusual for this form-factor (we'll discuss the cable system in more detail shortly). There are square vents in the butt end and two rows of oval ones in the top panel of the case.
The 300 and 350W models are expectedly very much alike in their interior design.
They differ in electrolytic capacitors installed at the output. The junior model has capacitors from United Chemi-Con and Rubycon there.
The higher-wattage model has Rubycon capacitors only (at least where we can read their marking).
The component density is very high, just as you can expect from a compact PSU that is supposed to deliver 300-350 watts of power, so we can't examine the components easily.
Anyway, we can see that these PSUs feature dedicated voltage regulation, the card with small DC-DC converter chokes being located above the output capacitors.
There’s a large daughter card that goes along the side of the case and is connected to the abovementioned voltage regulator card with a cable.
The standby source is based on an Infineon ICE2QR4765 chip which is employed in latest full-size ATX PSUs from Seasonic as well.
The mains connector and filtering circuitry are screened as is typical of Seasonic PSUs.
Cables and Connectors
The Seasonic SS-300M1U and SS-350M1U PSUs are equipped with the same selection of cables and connectors:
- One mainboard cable with a 20+4-pin connector (33 cm)
- One CPU cable with a 4-pin connector (34 cm)
- One cable with two PATA power connectors and a floppy-drive plug (35+15+15 cm)
- Two cables with two SATA power connectors on each (29+15 cm)
The cable system of these PSUs is quite original:
The whole bunch of cables is connected to the PSU with two connectors, as you can see.
The selection of component connectors is sufficient enough for a server PSU. As for desktop applications, the 350W model would benefit from a dedicated power connector for a PCIe graphics card if it were to be used in a gaming computer.