Meridian XCLIO 550W Power Supply

Interior of the XCLIO 550BL Power Supply:

The interior of the new XCLIO power supplies are completely different than the previous models (as can be seen here). In fact, the new XCLIO models are extremely similar to Antec's True Power 2.0 series (as can be seen here). Coincidence? Not really, Channel Well Technologies makes the Antec PSUs too, which explains why these two are so similar. While they might look identical at first glance, I did not compare all the various components, but I would venture to guess they are spec'ed accordingly.

On most power supplies (including the previous XCLIO models we looked at) there is a one group regulation choke with three windings. If you look in the picture below, you will see three (+3.3V, +5V, and +12V) chokes in a row with single windings (the ring cores with wires wrapped around them). Technically the 3rd has a secondary winding, but it is just for the -12V. This change, coupled with feedback circuits on each rail allow these power supplies to have tighter load regulation (±3% or better) than other power supplies (usually spec'ed at ±5% or better).

Lastly, yes the +12V rails are split, with the +12V ATX / EPS connectors on 12V2, and everything else on 12V1.

How We Test Power Supplies:

In order to thoroughly test a power supply we have built a special rig that is capable of dynamic load levels on each rail. A short article covering our power supply testing methodology in detail can be found here. Please read over the guide if you haven't already, you might just learn a thing or two. Simply plugging a power supply into a regular PC for "testing" is not accurate by any means, nor can any useful numbers be extracted by testing that way.

Also worth reading is our power supply primer article titled, Powering Your PC: Truths and Misconceptions - A Guide To Power Supplies, which covers how power supplies work in great detail.

If you have read the power supply testing article, you know that we publish four (4) groups of numbers for each power supply to give a simplified overall representation that can be compared to other power supplies. Many other load ranges are tested (but not published unless there is a serious problem) to ensure voltage levels remain within ATX12V specifications. I like to refer to it as "working the switchboard" since it involves flipping lots of switches tied to resistors on each rail to achieve various loads. Unfortunately we can't always dial in exact maximum numbers because of the fixed levels of resistance, but load levels we test are often far in excess of any load a regular PC will create.