Review of the Formula AP-500MM power supply

We continue our series of reviews of power supplies with the lowest retail price, and this time we’ll look at the Formula AP-500MM power supply. In total, the manufacturer has eight models of this series available with power from 400 to 750 W.

Particular attention is drawn to the fact that a significant part of the body is made in the form of a mesh. This can be done both to increase aesthetic appeal and to save materials. In any case, part of the warm air removed by the power supply fan through its internals will be distributed inside the system unit and not removed outside. The Formula AP-500MM unit also dissipates heat well. The power supply housing is painted black, which, in combination with the packaging, emphasizes the orientation of this model towards the retail market. The dimensions of the power supply are standard, the length of the case is 140 mm.

All necessary parameters are clearly indicated on the power supply housing. The power on the +12VDC bus is 450 W, which is 90% of the total power of the unit. This means that most of the power is available at +12VDC, which is important for modern systems. However, it is worth considering that this is a budget solution on not the newest platform, and this is not its only limitation.

• 1 cord: to the main ATX connector — 50 cm
• 1 cord: to the processor socket 8 pin SSI — 61 cm
• 1 cord: to the first PCIe 2.0 VGA Power Connector video card power connector — 55 cm, plus another 15 cm to the second same connector
• 2 cords: to the first SATA Power Connector — 45 cm, plus 15 cm to the second and another 15 cm to the third similar connector, plus another 15 cm to the Peripheral Connector (Molex)

The length of the wires in this power supply model is not the greatest, however, in modern medium-sized cases and with a hidden wiring system, there are no problems with assembly.

All wires are rigidly fixed, which is typical for budget solutions. In any case, their number is limited, which corresponds to the maximum power and indicates incompatibility with the assembly of high-performance systems.

SATA connectors are straight, which is convenient for connecting drives to the back of the motherboard base or other surfaces.

However, the distribution of connectors along the power cords may not be the most convenient for simultaneously connecting multiple devices at long distances from the power supply. In a typical system with a small number of drives this is not a problem, but in a mini PC it may require more careful planning.

It is worth noting the use of ribbon wires, which improves the ease of assembly and subsequent operation.

Overall, from a wiring perspective, this model offers ease of assembly, making it competitive with similar models.

The power supply is equipped with an active power factor correction, but has a standard rather than extended range of supply voltages.

The main semiconductor elements are placed on two small radiators. The first radiator houses the elements of the power factor corrector and the main AC inverter, and the second one houses the rectifiers.

The platform here is not the most advanced: it uses group stabilization of the +5VDC and +12VDC channels, as well as +3.3VDC on a separate stabilizer based on a magnetic amplifier. This is typical for low-budget solutions.

A Nichicon capacitor with a capacity of 220 µF is installed at the input. The remaining low voltage circuits are dominated by capacitors from ChengX.

The power supply contains a Xiongli Electronic W12025HZ12SEMA fan with a diameter of 120 mm. The PSU manufacturer claims that the fan is equipped with a hydrodynamic bearing. The fan connection is two-wire and detachable, which makes it easy to replace and also ensures trouble-free operation during the warranty period.

Next, we move on to analyzing the electrical characteristics of the power source using a multifunctional stand and other equipment.

The amount of deviation of the output voltages from the nominal value will be represented by color coding as follows:

The first stage of testing is to operate the power supply at maximum power for an extended period of time. This test allows you to verify the reliability of the power supply. In this case, we carried out the tests several times to avoid possible problems with overheating of the connectors due to their limited number.

The power supply is indeed capable of operating at the maximum declared power for a long time, however, in a real system it will be difficult to achieve this power due to the limited number of power connectors for video cards and the inability to significantly load the +3.3VDC and +5VDC channels.

KNKh allows you to determine what load level can be considered acceptable for the tested specimen, especially on the +12VDC channel. In this case, deviations of the effective voltage values ​​from the nominal value on the +12VDC channel exceed 3% with a load power of over 400 W. Deviations along the +5VDC channel are about 5% towards increasing values.

This behavior is often found in power supplies with group stabilization, but this model is no exception.

A study was carried out on the +5VDC channel, from which it follows that with a load of up to 230 W on the +12VDC channel, the deviation on the +5VDC channel does not exceed 4% of the nominal value. This deviation is observed with a typical load on the +3.3VDC and +5VDC channels, characteristic of modern systems.

The following test is aimed at determining the maximum power that can be transmitted through the corresponding connectors when the voltage tolerance is within 3% or 5% of the nominal voltage.

In the case of a video card with a single power connector, the maximum power over the +12VDC channel is at least 150 W with a deviation within 3%.

In the case of a video card with two power connectors, the maximum power via the +12VDC channel is at least 250 W with a permissible deviation within 3%. Medium-power video cards with this power supply should work without any problems.

When loaded through the processor power connector, the maximum power through the +12VDC channel is at least 250 W with a permissible deviation within 3%. For budget systems this is enough.

In the case of a motherboard, the maximum power on the +12VDC channel is at least 150 W with a permissible deviation within 3%. Considering that the board itself consumes about 10 W through this channel, high power may be required to power expansion cards, for example, video cards without an additional power connector, which usually have a consumption of around 75 W.

When assessing the efficiency of a computer power supply, you can approach it in two ways. The first approach is to consider the power supply as a separate device that converts electrical energy while minimizing losses along the transmission line to the load. To do this, the power supply is connected with all available connectors, which creates unequal conditions for different models, taking into account different sets of connectors and numbers of current-carrying wires.

However, in real-world applications, the power supply is usually connected through only a limited number of connectors, which makes the data obtained of little use for understanding its real efficiency. Therefore, a more logical approach to assessing the efficiency (cost-effectiveness) of a computer power supply is to use fixed power values ​​and power distribution across channels, taking into account a specific set of connectors for each model.

Efficiency ratings are often expressed in terms of coefficient of performance (COP), which reflects the ratio of the power supply's output power to its input power. For the average user, this parameter is not always clear, but it has become an important element of the marketing strategy, especially with 80Plus certification. In practical terms, high efficiency does not affect the performance or other characteristics of the system unit, but only indicates the efficiency and quality of the device.

On the other hand, to objectively assess the efficiency of a power supply, it is important to take into account the power dissipation, which is the difference between the input and output powers of the unit. This allows you to calculate actual energy consumption and assess the economic feasibility of using a specific power supply model over a long period of time.

Thus, the methodology for measuring power supply efficiency must be adapted to real-world usage conditions, taking into account the specific characteristics of the connectors and the power available for each model.

The results obtained look like this:

This model has low efficiency in all tested modes; it is a completely typical representative of power supplies in the budget segment, which are not chosen for efficiency.

In terms of power dissipation when operating at a low load (and this model cannot handle a high load), the Formula AP-500MM takes an honorable second-to-last place in the list of power supplies up to a kilowatt.

In this case, the thermal load of the capacitors remains at a low level throughout the entire power range, which is a positive aspect. This fact is explained not so much by high efficiency or high-quality design, but by the presence of a high-speed fan and many holes on different sides of the power supply case. Thanks to this, it was possible to effectively organize heat removal, including its distribution inside the system unit case.

To measure the noise level of power supplies, we used the following method. The power supply was placed on a flat surface with the fan facing upwards. At a distance of 0.35 meters from the block, a measuring microphone of the Oktava 110A-Eco sound level meter was installed to carry out measurements. The load on the power supply was carried out using a special stand that ensured silent operation. The power supply operated at constant power for 20 minutes, after which the noise level was measured.

This distance to the noise source is the closest to the situation where the system unit is placed on a desktop with the power supply installed. This method allows you to accurately estimate the noise level of the power supply in conditions where the user is close to the noise source. As the distance to the block increases and additional obstacles appear that reflect sound well, the noise level at the measuring point will also decrease, which helps to increase acoustic comfort in general.

When measuring the noise level of power supplies, we used the following approach. The power supply was placed on a flat surface with the fan facing upward. At a distance of 0.35 meters from it, an Octava 110A-Eco sound level meter was located to measure the noise level. The load on the power supply was carried out by a special stand that ensured silent operation. The power supply was operated at constant power for 20 minutes, after which the noise level was measured.

This method allows you to accurately determine the noise level of the power supply when it is located on a table in the near field from the user. As the distance to the block increases and barriers are used, the noise level at the measurement point also decreases, improving overall acoustic comfort.

The acoustic ergonomics of this power supply, one might say, do not stand out particularly, which is typical for its price category. However, at a power below 300 W, the noise remains at a level that is quite comfortable for most users. It is recommended to consider purchasing this power supply for systems whose consumption does not exceed 250-300 W. The +12VDC channel has sufficient load capacity, which is especially important for video adapters. The only potential problem may arise with the +5VDC channel due to long wires and less than optimal connectors. In general, the consumer qualities of this model can be considered satisfactory, especially considering its budget nature.

The Formula AP-500MM power supply is fully suitable for powering an entry-level system unit with a total power of up to 300 W (and also higher if you don’t mind listening to the fan). In typical modes, it shows adequate parameters and works successfully for a long time at high loads, which is a positive aspect. However, keep in mind that this is a budget product with its own features and limitations.