Antec Phantom 500

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ON THE TEST BENCH

For a fuller understanding of ATX power supplies, please read our article Power Supply Fundamentals & Recommended Units. Those who seek source materials can find Intel's various PSU design guides, closely followed by PSU manufacturers, at Form Factors.

For a complete rundown of testing equipment and procedures, please refer to the article SPCR's Revised PSU Testing System. It is a close simulation of a moderate airflow mid-tower PC optimized for low noise.

In the test rig, the ambient temperature of the PSU varies proportionately with its output load, which is exactly the way it is in a real PC environment. But there is the added benefit of a precise high power load tester which allows incremental load testing all the way to full power for any non-industrial PC power supply. Both fan noise and voltage are measured at various standard loads. It is, in general, a very demanding test, as the operating ambient temperature of the PSU often reaches >40°C at full power. This is impossible to achieve with an open test bench setup.

Great effort has been made to devise as realistic an operating environment for the PSU as possible, but the thermal and noise results obtained here still cannot be considered absolute. There are far too many variables in PCs and far too many possible combinations of components for any single test environment to provide infallible results. And there is always the bugaboo of sample variance. These results are akin to a resume, a few detailed photographs, and some short sound bites of someone you've never met. You'll probably get a reasonable overall representation of that person, but it is not quite the same as an extended meeting in person.

REAL SYSTEM POWER NEEDS: One very important point is that the while our testing loads the PSU to full output (even >600W!) in order to verify the manufacturer's claims, real desktop PCs simply do not require anywhere near this level of power. The most pertinent range of DC output power is between about 65W and 250W, because it is the power range where most systems will be working most of the time. To illustrate this point, we recently conducted system tests to measure the maximum power draw that an actual system can draw under worst-case conditions. Our most powerful P4-3.2 Gaming rig drew ~180W DC from the power supply under full load — well within the capabilities of any modern power supply. Please follow the link provided above to see the details. It is true that elaborate systems with SLI could draw as much as another 150W, but the total still remains well under 400W in extrapolations of our real world measurements.

The extra length of the Phantom 500 is obvious; it doesn't fit properly on our test bench.

Ambient conditions during testing were 21°C and 20 dBA, with input of 120 VAC / 60 Hz measured at the AC outlet. This is slightly warmer and louder than is typical in the lab. All testing was done with the Phantom 500 fan controller switch at "3", the least aggressive setting for fan cooling .

TEST RESULTS

ANTEC PHANTOM 500 TEST RESULTS
DC Output (W)	65	90	150	200	250	300	400	500
AC Input (W)	83	111	177	227	278	337	452	566
Efficiency	78%	81%	85%	88%	90%	89%	88%	88%
Intake Temp (°C)	26	28	32	35	37	39	43	44
PSU Exhaust (°C)	40	40	44	46	46	48	52	56
Fan Noise (dBA/1m)	n/a	n/a	n/a	24	29-32	35	36	37
Power Factor	0.57	0.58	0.60	0.62	0.63	0.65	0.67	0.68
NOTE: The ambient room temperature during testing varies a few degrees from review to review. Please take this into account when comparing PSU test data.

Please note -- you may need to refer back to the article, SPCR's Revised PSU Testing System, to understand the following discussion fully.

1. VOLTAGE REGULATION was well within the ±5% claimed. Throughout the range of test power output levels, the range was as follows:

• +12V: 11.9 ~ 12.1 V
• +5V: 4.8 ~ 5.0 V
• +3.3V: 3.1 ~ 3.3 V

2. AC-to-DC CONVERSION EFFICIENCY

As mentioned, the Phantom 350 peaked at a record 88% efficiency at 300W when we tested it last September. We were expecting the Phantom 500 to perform at least as well, and we were not disappointed. The Phantom 500 surpassed its smaller brother and peaked at 90% efficiency: A new record! Even better, this peak was reached at 250W output instead of 300W, meaning that the Phantom 500 will likely provide more benefit to real systems in real applications (at lower power) from its high-efficiency design than the original version.

One thing that we noticed was the wide variation in the efficiency of the 350W version, which ranged from 72% at 65W to 88% at 300W. The Phantom 500 is much better in this regard, starting with a high 78% at the 65W mark. It has a much flatter efficiency curve. At 90W output and higher, the Phantom always ran well above 80% efficiency, an impressive achievement unmatched by any other power supply we've tested so far. Above 200W output (where the internal heat production of a power supply is signficantly higher) efficiency never dropped below 88%. (Note that these figures apply to the more efficient non-PFC North American version.)

3. POWER FACTOR

Our review sample was the North American version, which does not feature PFC. Power factor ranged from 0.57-0.68, which is typical of non-PFC power supplies. The European and UK versions of Phantom both feature active PFC that is rated for >0.95 power factor. Antec states that these models are 4% less efficient than the North American version.

4. TEMPERATURE

The exhaust temp sensor was placed in one of the exhaust vent holes on the back panel of the PSU. The intake temp sensor was left where it has been for all the PSU reviews going back at least a year: One inch below and behind the PSU, inside the thermal test box.

Unlike all of the other power supplies we've tested, the difference between the intake and exhaust temperatures was greatest at low output levels. This result reflects the hybrid design of the Phantom 500. When the fan is not spinning, all the heat generated by the power conversion process is only removed by condution and convection, so the unit gets fairly warm. At higher output levels, the temperature climbs higher and the fan begins to spin, thus exhausting the heat more efficiently and keeping the unit cooler.

Even at its full 500W output, the Phantom stayed surprisingly cool. The exhaust temperature never rose above 60°C, a level that is occasionally broken even by units with much larger, more powerful fans. The fan ramps up quickly enough that past 35°C intake temperature (200~250W load in our test setup and conditions), the temperature difference between exhaust and intake stayed at ~10°C, which is similar to that seen in high efficiency conventional fan-cooled PSUs.

It is interesting to note that the Phantom 350 is specified for safe operation up to 65°C, wherever this temperature is actually measured. In contrast, the Phantom 500 is rated for an operating temperature up to 50°C. Why should this be so?

Here's one hypothesis: The Phantom 500 is essentially a Phantom 350 with a fan. It is because the fan keeps temperature lower that the Phantom 500 can be allowed to run at higher output. In other words, if active airflow cooling was applied to the Phantom 350, and its overload protection settings changed, it could also safely produce 500W.

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