Contents
Besta PT-500
Those of you who knew me before Hardware Insights existed may remember that I once did a more basic review on an identical unit to this. To cut a long story short, it turned out to be more of a “worsta”. It’s voltage regulation was poor and it exploded long before we hit the the labelled rating. Now that I have a bit of extra testing equipment, and another unit, why not include it as part of this roundup?
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The fact that a new unit still has more current on the 5v rail than on the 12v shows that whoever designed this unit must still be using old Socket A based computers. That was the last socket where more than 30A on the 5v rail was required. Nowadays, it’s the 12v rail where the current needs to be.
Load Testing
Test 1 (120.76W Load – Cold)
| Rail | Load | Voltage | Ripple |
| 12V | 4.9A | 12.24V | 33.7mV |
| 5V | 5.12A | 5.12V | 14.4mV |
| 3.3V | 10.24A | 3.38V | 20.0mV |
| −12V | 0A | −12.15V | 10.0mV |
| 5Vsb | 0A | 5.13V | 5.62mV |
| AC Power | 147.6W | ||
| Efficiency | 81.82% | ||
| Power Factor | 0.62 | ||
Test 2 (212.9W Load – Cold)
| Rail | Load | Voltage | Ripple |
| 12V | 9.72A | 12.15V | 45.6mV |
| 5V | 10.18A | 5.09V | 19.4mV |
| 3.3V | 10.45A | 3.45V | 31.3mV |
| −12V | 0.1A | −12.23V | 24.4mV |
| 5Vsb | 1.01A | 5.03V | 48.8mV |
| AC Power | 248.9W | ||
| Efficiency | 85.29% | ||
| Power Factor | 0.6 | ||
Test 3 (237.02W Load – Cold)
| Rail | Load | Voltage | Ripple |
| 12V | 12.02A | 12.02V | 51.3mV |
| 5V | 10.16A | 5.08V | 16.9mV |
| 3.3V | 10.24A | 3.38V | 30.0mV |
| −12V | 0.1A | −12.33V | 22.5mV |
| 5Vsb | 1A | 5.02V | 40.6mV |
| AC Power | 282W | ||
| Efficiency | 84.05% | ||
| Power Factor | 0.59 | ||
Test 4 (291.08W Load – Cold)
| Rail | Load | Voltage | Ripple |
| 12V | 14.48A | 12.07V | 56.3mV |
| 5V | 15.09A | 5.03V | 13.1mV |
| 3.3V | 10.15A | 3.35V | 31.3mV |
| −12V | 0.11A | −12.70V | 26.9mV |
| 5Vsb | 1A | 5.00V | 60.6mV |
| AC Power | 345.7W | ||
| Efficiency | 84.20% | ||
| Power Factor | 0.6 | ||
Test 5 (348.38W Load – Cold)
| Rail | Load | Voltage | Ripple |
| 12V | 14.48A | 11.88V | 65.6mV |
| 5V | 15.18A | 5.06V | 31.9mV |
| 3.3V | 20.24A | 3.34V | 29.4mV |
| −12V | 0.11A | −12.91V | 26.3mV |
| 5Vsb | 1A | 4.99V | 81.9mV |
| AC Power | 419.52W | ||
| Efficiency | 83.04% | ||
| Power Factor | 0.6 | ||
This unit actually performed quite well for a cheaper power supply. The voltages did actually stay within spec and the efficiency was above 80% the whole time. The ripple was in check too until we hit test 4 at about 290W. The ripple on the 5vsb then went out of spec. During test 5 at about 350W, the unit failed shortly after I finished reading all of the parameters. It didn’t explode like my last PT-500. It just shut down and wouldn’t start up again.
| Rail | Test 4 (291.08W) | Test 5 (348.38W) |
| 12V |  |
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| 5V |  |
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| 3.3V |  |
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| −12V |  |
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| 5Vsb |  |
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A look inside
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It’s pretty much identical internally to my last Besta PT-500. The input filtering is mostly there, although it still needs an extra coil and an MOV. It also has a 4A bridge rectifier, rather than the 4 individual diodes commonly used in cheaper units. Unfortunately, though, the two primary capacitors are only 470μF parts from an obscure manufacturer called QMLCON. I couldn’t identify the manufacturer or find a datasheet for the switching transistors either. The part number printed on them is simply “13007”, which is a generic part number used by several manufacturers, so it really doesn’t tell us anything. Like the other 7 power supplies in this round up, the PT-500 uses a dated half bridge design.
Bolted to the secondary heat sink, the output rectifiers used are two MOSPEC F12C20C fast recovery rectifiers for the 12v rail. This gives a total of 24A on the 12v rail. It’s more than enough to do what the label says, but it would have been better to use a Schottky rectifier, since they offer better efficiency and thus they don’t heat up as much and I might not have burned my fingers from touching the heat sink. The 5v rail has a single STPS3045CW Schottky rectifier rated at 30A, which is not enough for the 37A on the label. The rectifier on the 3.3v rail looks to be from the same manufacturer as the primary switching transistors, which I couldn’t identify. The part number is simply “20S45”, which suggests it’s a 20A part. Again, it’s insufficient for the 28A rating. The capacitors on the secondary side are all BH, which are of questionable quality.
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The fan has no branding on it, nor does it have a UL number, so it’s another part I can’t identify the manufacturer of. That said, I’ve seen that logo on a few other fans before and and most of them were seized up or really noisy, so it’s unlikely to be a high quality part. The PT-500 lacks a fan controller, so the fan just runs at its maximum rated speed regardless of the temperature. However, the unit was still fairly quiet, so the fan is probably a low speed model.
Actual specifications
| Real Wattage | 290W |
| OEM | Unknown |
| PFC | None |
| Price | $30 (AUD) |
| ATX Connector type | 20+4 pin |
| Worst-case voltage regulation (12v, 5v, 3.3v) | 2%, 2.4%, 4.5% |
| Worst-case ripple (12v, 5v, 3.3v) | 65.6mV, 31.9mV, 31.3mV |
| Worst-case efficiency | 81.82% |
| Input filtering | Inadequate |
| CPU Connector | ATX12v (4 pin) |
| PCIe Connectors | None |
| Molex (Peripheral) Connectors | 4 |
| FDD Power connectors | 1 |
| SATA Power connectors | 1 |
Conclusions
Pros: Voltage Regulation, Efficiency
Cons: Couldn’t deliver 500W, Inadequate Input filtering, Only 1 SATA connector, Low quality fan and capacitors, No PFC, More current available on 5V rail than on 12V rail
Bottom Line: The performance was good for a cheap unit, but it doesn’t have enough connectors, can’t deliver 500W and uses low-quality parts.
Score: 4/10
Right, let’s move on to our next victim, and see if we can get better results or better fireworks.
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