ST-550P-AG is an entry-level 550 W power supply from Seventeam, featuring active PFC, a 120 mm fan and only two SATA power connectors. Let’s see if this unit can really deliver 550 W and whether it is a good product or not.

One funny detail is the sticker in Engrish saying “Breakage Invalid” instead of “Warranty Void if Broken.”

Seventeam ST-550P-AGFigure 1: Seventeam ST-550P-AG power supply.

Seventeam ST-550P-AGFigure 2: Seventeam ST-550P-AG power supply.

This power supply is very small, being only a 5 ½” (140 mm) deep. It uses one brushless 120 mm fan on its bottom and as you know this cooling solution is better than using one or two 80 mm fans, as a 120 mm or bigger fan can produce a bigger airflow rotating at a lower speed, what reduces the noise produced by the fan.

Funny enough Seventeam’s website does not feature this product, but we could find the original spec sheet here. According to the manufacturer this power supply has a 78% maximum efficiency.

As mentioned, this power supply features active PFC, what enables Seventeam to sell this product in Europe.

The main motherboard cable uses a 20/24-pin connector and it comes with both EPS12V and ATX12V connectors, sharing, however, the same cable.

Seventeam ST-550P-AG comes with five peripheral cables: one with two 6-pin auxiliary power connectors for video cards, one with two SATA power connectors, two with three peripheral power connectors and one with two peripheral power connectors and one floppy disk drive power connector.

Even though all wires are 18 AWG – which is the right gauge for a 550 W product – there are two flaws here. The first one is the presence of only two SATA power connectors. Since nowadays you will have at least two SATA devices – the hard disk drive and the optical drive – you will have trouble installing a second hard disk drive (you will need an adapter). This may indicate that this unit uses an older project from when SATA peripherals were not the norm (we will see if our suspicion holds true after disassembling it and analyzing its project).

The second problem is that even though this power supply has two auxiliary power connectors for video cards, they are attached to the same cable. Ideally each connector should use its own cable.

On the aesthetical side only the main motherboard cable uses a nylon sleeving, which comes from inside the power supply housing.

Seventeam is one of the few real power supply manufacturers around. They are the company behind of power supplies from XG/MGE and some models from Cooler Master.

Now let’s take an in-depth look inside this power supply.


Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.