Review of the Chieftec Smart BFX-450BS SFX format power supply unit with a power of 450 W / Overclockers.ua

Today we are testing an SFX format power supply — Chieftec BFX-450BS. This is the oldest model in the Smart series, which also includes a 350W unit. They replaced the already outdated SFX-350BS and SFX-450BS units, also with the 80 Plus Bronze certificate and quite similar characteristics. Let’s see what new Chieftec has to offer in budget compact blocks.

Chieftec Smart BFX-450BS

The delivery set is minimal, the power supply unit came in a package, without a power cable.

The body of the unit is not painted, the cooling fan grill is stamped, there is a black sticker on the side, which improves the appearance of the body at least a little.

On the upper face is a sticker with the technical characteristics of the device.

Power supply unit with soldered cables, their number and length are as follows:

• one for powering the motherboard (35 cm);
• one with another 8-pin (4+4) processor power connector (35 cm);
• one with two 8-pin (6+2) connectors for powering a PCI-E video card (35+15 cm);
• one with two power connectors for SATA devices and one connector for IDE devices (35+15+15cm);
• one with one power connector for SATA devices, one connector for IDE devices and one FDD connector (35+15+15 cm).

All cables are made of multi-colored wires, the motherboard power cable is black nylon braided.

The unit is built on a CWT platform with an active power factor corrector (APFC) and a wide input voltage range. The power converter on the +12 V line is made according to the oblique bridge scheme without a synchronous rectifier, for the +5 V and +3.3 V lines, DC/DC converters are used, while in the old units, group stabilization of the output voltages was used.

A full-fledged impulse interference filter is unsoldered on the input board, some of its elements are located on the network connector. The input rectifier is mounted on a small separate radiator, it was not possible to consider the type of diode bridge. The corrector and power converter are controlled by a PWM controller installed on a separate board (the marking of the chip was not visible). A pair of transistors and diodes are installed in the power part of the corrector, but it was also not possible to determine their type. The high-voltage filter is made of a pair of electrolytic capacitors with a capacity of 120 μF with an operating voltage of 400 V and a temperature of 105 °C manufactured by ChengX. The total capacity of the filter is 240 μF.

A pair of power converter transistors are mounted on a common radiator with APFC elements. All radiators in the block are made of rather thin plates, but the saving grace is that they are based on an anodized copper alloy, and if you scratch the white coating, you can see the red metal. The output rectifier is made of four Schottky diodes PFR30L60CT (30 A, 60 V), the voltage is filtered by three 1000 μF 16 V 105 °C electrolytic capacitors manufactured by ChengX. The output choke is slightly raised above the output capacitors, which is a plus, because often in such units the choke is installed close to the capacitors, which interferes with the cooling of the choke and leads to more heating of the capacitors.

A step-down DC/DC converter assembled on a separate board is responsible for powering the +3.3 V and +5 V lines. A pair of polymer capacitors of 470 μF 16 V are installed on it at the input of the converter, a pair of chokes and a pair of polymer capacitors with a capacity of 1500 μF with a voltage of 6.3 V at the output, the type of controller could not be determined. Additionally, voltages on these lines are filtered by several polymer capacitors near the place where the wires are soldered.

The power converter of the standby mode is made on a PWM controller TNY177PN, at its output are installed electrolytic Low ESR capacitors with a capacity of 2200 μF with an operating voltage of 16 at 105 °C manufactured by ChengX. All other capacitors in this harness and power converter are also from ChengX. The output voltage is monitored by the ST9S313-SAG supervisor from Sitronix.

Cooling of the unit components is handled by a 92x92x15 mm fan marked HA9215H12F-Z (12 V, 0.22 A) with a two-pin connection. The fan is controlled automatically, depending on the temperature of the power components of the unit. After turning on the unit without load, the fan is quite quiet and does not stand out against the background of other fans of the test bench, as the temperature rises, it should smoothly increase the speed of rotation.

The installation is a bit careless, some components are not installed exactly straight, there are no complaints about the rutting, everything is soldered normally and the board is washed from the flux.

Testing methodology

The power supply unit was tested using a linear electronic load with the following parameters: current adjustment ranges on the +3.3 V line — 0–16 A, on the +5 V line — 0–22 A, on the +12 V line — 0–100 A All contacts for connecting power supply cables with the same voltage are connected in parallel and loaded by the corresponding load channel. The current on each channel is smoothly regulated, and it is stable, regardless of the output voltage of the unit. A Zotek ZT102 True RMS multimeter was used to accurately measure voltage and temperature. For each power line, the required current was set, and the voltage was measured at the load contacts to account for wire losses.

Test results

The first test for the load capacity of the +12V main line, the current on the +3.3V and +5V lines was constant with a total load of about 120 W.

According to the test results, we have good stabilization on all lines, there are small sags, but this is a problem with cheap wires. A measurement was made on an unloaded SATA connector to obtain the voltages on the unit board itself without taking into account the voltage drop on the wires. And as you can see, there are no drafts on the block itself.

To check the load capacity of the +5V and +3.3V lines, tests were made at a constant load of +12V to assess their influence on each other.

According to the test results, we have normal stabilization on the +3.3V and +5V lines, the load distortions are small and fit within the ATX norms.

The block efficiency test was carried out at a network voltage of about 230 V.

The efficiency of this unit is included in the 80 Plus Bronze standard for a voltage of 230 V.

The test for heating the unit components was carried out at an indoor air temperature of 25 °C. It was loaded at maximum power and worked until the temperatures stabilized. At the end of the test, the block cover was removed and component temperatures were measured using a multimeter and its thermocouple. The test results are shown in the following photo of the block board:

The temperatures of the components turned out to be small, as for a “bronze” block in a compact case, and they are typical for ATX blocks. At long-term maximum load, the device remained relatively quiet and did not stand out against the background of other fans of the stand, despite its small size. In an assembled PC, the temperature and noise of the unit will be higher, everything will depend on its location, size and air permeability of the case, as well as on the air temperature in the room.

Conclusions

The tested Chieftec Smart BFX-450BS delivers all the declared characteristics at a relatively low noise level. From the pros, we can note the use of DC/DC converters with independent stabilization of low-voltage channels, from the cons – budget components and cables. This unit is perfect for inexpensive mini-systems, but you need to take into account that the wires are soldered and there may be problems with installation in very compact cases. In addition, its price is not much lower than the modular Chieftec CSN-450C, which, moreover, has a “gold” certificate. As a result, the price will be the deciding factor, but so far it is too high for such a power supply.