We were somewhat impressed by the performance of Seventeam ST-550P-AG in our tests. Even though this is a low-end product it could not only really deliver its labeled power at 50º C, but we could pull up to 630 W from it at 49º C. Not bad at all.
Differently from Seventeam ST-420BKV the reviewed model uses an updated design with active PFC, power MOSFET transistors on the switching section and rectifiers for the +12 V output that are bigger than the ones used on the +5 V and +3.3 V outputs.
Efficiency is good (i.e. above 80%) if you pull up to 80% (440 W) of its labeled power. If you, however, pull 550 W or more from it you will see efficiency below the 80% mark.
But honestly we don’t think someone buying this power supply would ever come close to its labeled power, so this should not be an issue for the user this power supply is targeted to.
The only real problem with this power supply is the extremely low number of SATA power connectors – only two. If you want to install more than two SATA devices you will have to use adaptors to convert standard peripheral power plugs into SATA power plugs.
If this limitation doesn’t bother you, this unit provides a terrific cost/benefit ratio, mainly because of its price. Of course more expensive models will provide more features, like modular cabling system, more SATA power connectors and even more video card power connectors.
