The PSU we'll be looking at in this review is a representative of the A135 series, which includes PSUs ranging from 350W to 850W.
This product comes in a small cardboard box. The text on the packaging lists the various benefits of this power source, but does not mention any specific characteristics.
The UL certification number E320351 indicates that this PSU was manufactured for the Chieftec by Sirfa, which has already been tested in our lab. If the name of the company doesn't tell you anything, it should be said that Sirfa was founded two years ago, it spun off from Sirtec Fab. And Sirtec itself should be familiar to you from our PSU reviews.
Exterior and interior design, cables and connectors
The power supply is housed in a simple gray box of almost standard size. Its width is 160 millimeters, which makes it possible to install a 140mm fan. Note the shape of the case around the fan: Chieftec appears to have implemented Enermax's idea of making the gap between the case and the fan smaller in order to reduce the fan's noise level (by a few decibels, according to Enermax).
Inside the case, you can see the typical arrangement of modern power supply components: the power components are located on three heatsinks, which are simple non-corrugated aluminum plates. This should be sufficient for cooling given the high efficiency and low power dissipation of the power supply electronics. This product employs an active PFC circuit.
This product uses high performance Teapo capacitors, which enjoy a good reputation, so you can expect a long service life. As for the build quality and soldering, they are at a good level.
The power supply has the following cables and connectors:
Motherboard cable with 24-pin connector (42 centimeters)
Processor cable with 8 - and 4-pin connectors (41 +16 cm)
Additional power cable for graphics cards with two 6-pin connectors (41 +16 cm)
One cable with three Molex connectors and one floppy connector.
Two cables with three SATA power connectors each.
There are some criticisms of this set of cables and connectors. The fact is that there is no second connector for a video card, despite the fact that the power supply unit has enough power to power older models of video cards with two power connectors. And it should be noted that the cables are relatively short. They may not be long enough to connect hard drives in a large computer case. In the event that the PSU is installed in the lower bay of the case, and this method of installation is becoming more and more popular, the processor cable will almost certainly be too short.
Passport parameters
The power supply has a rated power of up to 550 W and can provide up to 450 W on the +12 V line. Therefore, its effective power (i.e. what you can get from it in a real computer, which is powered mainly by the + 12 V) is about 500 W, which is a good indicator. The + 12V rail is divided into two virtual lines of 25 amps each.
Stability of output voltages
The APS-550S provides stable voltages, especially when you consider that it uses group voltage regulation. Indeed, voltages go out of range when the total load has an imbalance of +5 V and +3.3 V, which simply cannot happen in a real computer.
Our reference configurations (marked with crosses in the diagram) are in the green zone, which means that the output voltage deviates by no more than 3% from the required level.
Output voltage ripple
The output ripple at full load is just above the +5 V tolerance limit, but you don't have to worry about those single, brief spikes above the 50-millivolt level. They will not affect the stability of your computer.
Noise level
This PSU is cooled by a Globe Fan RL4Z S1352512H, which is partially covered by a plastic cover to allow air to flow into the rear of the PSU case. Consequently, the entire volume of the PSU will be well ventilated.
Blover spins at less than 700 rpm and is virtually silent at low loads. At loads above 200 W, its rotation speed grows linearly, and at loads of 300-350 W, it already becomes audible. The maximum fan speed is 1430 RPM, but the noise remains acceptable even in this case.
UPS compatibility
Together with our UPS (model APC SmartUPS SC 620), the power supply in question was operated at a load of up to 370W on mains supply. But when it switched to the UPS batteries, the uninterruptible power supply would normally shut down for just a couple of seconds at 350W and 3 to 5 seconds at 300W. Therefore, the reviewed power supply APS-550S has sufficient compatibility with uninterruptible power supplies. It is recommended to use a UPS with a sinusoidal output voltage, or with a high power reserve with this power supply.
Power factor and efficiency.
The power supply unit has good, but not a record, efficiency at the level of 85-86%. On the positive side, the efficiency is not very dependent on the load, with a load of 60 W it drops to 83%.
Power supply in Standby mode.
Standby power is rated for 2.5 amps and does its job very well. Its voltage is slightly lower than the required 5 volts at full load.
conclusions
The only complaint about the Chieftec APS-550S power supply is its insufficient cable length. The fact is that there are a small number of large-sized cases designed for enthusiasts, for whom a 42 cm cable will cause some inconvenience when connecting the motherboard, but, in general, this is a rare case. And if you own a mid-sized case, the APS-550S is an excellent choice as it is a high quality, stable, quiet and reasonably priced PSU.
