The 2013 El-Cheapo Power Supply Round-up

Bliss ATX-350

My experience with Bliss Products is fairly limited. The few I have run into over the years have been mostly low end products which didn’t impress me with their build quality. Given that this model is available for only $30 from some retailers, my prediction is that it will be anything but blissful.


The label indicates that this unit uses a dated 5V-heavy design, which hasn’t been practical for the last decade. The power supply itself is a plain grey colour. Unfortunately, the ventilation is poor, with just a row of slots in the front as the intake.

Load Testing

Test 1 (119.55W Load)

Rail Load Voltage Ripple
12V 4.89A 12.22V 58.0mV
5V 5.06A 5.06V 18.8mV
3.3V 10.18A 3.36V 19.8mV
−12V 0A −12.82V 18.8mV
5Vsb 0A 5.03V 10.4mV
AC Power 146.88W
Efficiency 81.39%
Power Factor 0.61


Test 2 (209.49W Load)

Rail Load Voltage Ripple
12V 9.78A 12.22V 76.4mV
5V 9.98A 4.99V 20.8mV
3.3V 10.15A 3.35V 18.6mV
−12V 0.1A −12.3V 56.8mV
5Vsb 1A 4.98V 15.6mV
AC Power 247.72W
Efficiency 84.57%
Power Factor 0.6


Test 3 (267.61W Load)

Rail Load Voltage Ripple
12V 14.58A 12.15V 93.0mV
5V 10.02A 5.01V 22.6mV
3.3V 10.15A 3.35V 19.09mV
−12V 0.1A −12.49V 74.0mV
5Vsb 1A 4.98V 17.2mV
AC Power 318.27W
Efficiency 84.08%
Power Factor 0.6


Test 4 (323.23W Load)

Rail Load Voltage Ripple
12V 19.28A 12.05V 112.2mV
5V 10.08A 5.04V 28.6mV
3.3V 10.12A 3.34V 19.0mV
−12V 0.11A −12.65V 88.2mV
5Vsb 1A 4.98V 17.4mV
AC Power 391.4W
Efficiency 82.58%
Power Factor 0.62


The 12V rail varied between 12.22V in Tests 1 and 2 and 12.05V in Test 4. This equates to 1.83% regulation, and 1.42% variation. The 5V rail managed 1.2% regulation and 1.4% variation, while the 3.3V rail managed 1.81% regulation with 0.61% variation. That is good regulation, as ATX standards allow for up to 5%. However,  many power supplies can do better in terms of variation, keeping the voltages more constant.

The efficiency wasn’t too bad for a low end product,  peaking at 84.57% during Test 2. The power factor never made it past 0.62. This is a fairly poor result, but it’s typical of power supplies that lack PFC. I did attempt a fifth test, with the power supply loaded to 350W (it’s rating), but the switching transistors exploded during that test.

Rail Test 3 (267.61W) Test 4 (323.23W)
12V  Test3-12v  Test4-12v
5V  Test3-5v  Test4-5v
3.3V  Test3-3.3v  Test4-3.3v
−12V  Test3--12v  Test4--12v
5Vsb  Test3-5vsb  Test4-5vsb


The ripple was well suppressed on 5V, 3.3V and 5Vsb rails, staying well within limits at all times. The 12V and −12V rails were a different matter. While they were both in spec, the ripple was above half the maximum limit. On the 12V rail, it was coming very close to the 120mV limit, with less than 10mV of headroom.



The input filtering consists of two X capacitors, two common-mode chokes and five Y capacitors (including the one after the rectifier), but there are no MOVs for surge protection. The bridge diodes are rated at 3A, and the primary capacitors are 470µF parts made by 12Kuang Jin. The switching transistors are (now rather charred) Huashan KSH13007s rated at 8A in the dated half-bridge configuration. Unlike most $30 power supplies, this one uses a switching IC for the 5vsb, rather than the more failure-prone 2-transistor circuits. The IC used is an ST Micro VIPer22A. The PWM controller is an SDC2921.

Moving on to the secondary side, the 12V rail employs a Mospec F20C20C Fast Recovery rectifier rated at 20A. This rectifier is good enough to deliver the 18A claimed by the label, but it would be better use use a Schottky rectifier as they offer better efficiency. The 5V and 3.3V rails both use a Mospec S20C45C schottky rectifier, which is also rated at 20A. This is just good enough for the 3.3V rail, as the label claims it to be capable of 20A, but a more powerful part should have been used on the 5V rail, as it is supposed to be capable of 35A. The capacitors on the secondary side are all made by Nicon. The quality of these parts is questionable, which raises some concern about the long term reliability of this product.


It looks like Mary is back with her little Wam. The fan was fairly quiet, but unfortunately, the lubricant in the bearings was insufficient. The heat sinks do have reasonable surface area, but are very thin, so they won’t conduct heat away from the silicon and up to the fins as well as thicker heat sinks would.

Specifications and Conclusions

Real Wattage 320W
OEM Unknown, Possibly XHY (Xin Hui Yuan) Power
PFC None
Price Unknown
ATX Connector type 20+4 pin
Worst-case voltage regulation (12v, 5v, 3.3v) 1.8%, 1.2%, 1.8%
Worst-case ripple (12v, 5v, 3.3v) 112.2mV, 28.6mV, 19.8mV
Worst-case efficiency 81.39%
Input filtering Adequate
CPU Connector ATX/EPS12V (4+4 pin)
PCIe Connectors None
Molex (Peripheral) Connectors 4
FDD Power connectors 2
SATA Power connectors 2


Pros: Good input filtering, Good Voltage Regulation, Quiet

Cons: Can’t deliver labelled rating (−2), Low quality capacitors (−2), Low quality Fan (−2), Mediocre 12V ripple suppression (−0.5), Old 5V-Heavy design (−0.5)

Score: 3/10

Pages: 1 2 3 4 5 6 7 8 9 10 11 12