We were impressed by the performance of Seventeam ST-550P-AM 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 671 W from it at 47.7º C. Not bad at all.

We thought ST-550P-AM would be internally identical to ST-550P-AG but we were wrong: this is a different product, with different rectifiers on the secondary (the primary from both units is identical).

Efficiency was around 83% when we pulled between 40% and 60% from the labeled capacity (between 220 W and 330 W). The problem was during full load, where efficiency was a little bit below 80%, at 79.8%.

Ripple and noise level were at very low levels all the time.

The only real problem with this power supply is the extremely low number of SATA power connectors – only two – and the presence of only one video card auxiliary power connector. If you want to install more than two SATA devices, more than one video card or a high-end video card that requires two power connectors you will have to use adaptors. Fortunately Seventeam corrected this issue on the newer shipments from this power supply, adding two SATA power cables with two connectors each and two cables for video cards.

If this limitation doesn’t bother you, this unit provides a terrific cost/benefit ratio. Of course more expensive models will provide more features, like modular cabling system, more SATA power connectors and more video card power connectors.

The low number of connectors and the efficiency a little bit below 80% at full load are the reasons we are giving it our “Silver Award” instead of our “Golden Award”.