The price
of energy is increasing world wide, so any reduction in the amount of power a
computer draws is a welcome change in our books. Power supplies which employ
Power Factor Correction (PFC, or A-PFC) help ensure efficient conversion of AC
to DC voltage, and reduce the amount of energy wasted as heat. The following
power supply tests were all conducted with an Extech Model 380803 Power Analyzer
located between the mains 120AC supply and the power supply, and with a 120W
dummy load. Power jitter is measured with a Mastech MS8230B Multimeter at the
device power connectors. The test apparatus and power meters are shown below.
Here is a picture of the test set up which
we will use to evaluate the Seasonic M12 700W power supply. The power supply looking device
is actually a 120W dummy load.
Power Jitter Observations -
Motherboard |
|
Voltage
jitter is read by accessing the power options displayed in the motherboard BIOS, with the system obviously in an unloaded state. *All voltages were read from the BIOS of an Asus A8N-SLI Premium motherboard.
|
Power Jitter Observations
- Motherboard |
|
Listed Voltages |
Lower Voltage |
Upper Voltage |
Jitter |
|
+3.3V |
3.3V |
3.33V |
0.03V |
|
+5.0V |
4.96V |
5.00V |
0.04V |
|
+12V |
11.8V |
11.9V |
0.1V |
|
-12V |
11.99V |
11.99V |
0V |
|
-5.0V |
5.00V |
5.00V |
0V |
|
+5.0Vsb |
5.00V |
5.00V |
0V |
The
voltage rails in the BIOS fluctuate a little bit but
it's nothing out of the
ordinary. The Seasonic M12 700W performs pretty well here but let's check out what the multi meter
says.
| Power Jitter Observations
- Multi-meter |
|
Voltage jitter was read by a Mastech MS8230B Multimeter with the system in an
unloaded state. During testing the power supply is was still connected to a full
computer and voltage values.
|
Power Jitter Observations
- Multi-Meter |
|
Listed Voltages |
Lower Voltage |
Upper Voltage |
Jitter |
|
+3.3V |
3.2V |
3.2V |
0V |
|
+5.0V |
5.0V |
5.0V |
0V |
|
+12V |
12.00V |
12.00V |
0V |
The important power lines are a lot more stable according the the multimeter, but then again BIOS readings have always been sketchy.
When looking at the Seasonic Power Supply test results we see two values, wattage
and volt-amps. Since it might not be clear what they measure, here's a brief
overview.
The
volt-amp (VA) value is how much real power is being consumed by the power supply
being tested to provide the wattage (W) value. The higher the VA value is, the
more electricity is being used by the power supply. Because no electrical device
is 100% efficient, there will always be some loss when converting AC to DC. The
closer the volt-amps and wattage figures are to each other, the more efficient a
power supply is. This is called the Power Factor: wattage / volt-amps = PF.
Since we're testing with a 120W dummy load, the
load on the power supply (wattage) should be as close to this figure as
possible. Anything above this load in apparent power describes the overhead and
wasted energy (given off as heat) for the particular power supply being tested.
For the unloaded tests, the wattage and volt-amp figures should be as close as
possible to one another. The lower the figures are, the less power is being
wasted.
Measurements were taken with an Extech 380803 Power Analyzer.
| Seasonic Power Load Tests |
| Power Supply Model |
Wattage |
Test Type |
Loaded |
Unloaded |
| Seasonic SuperTornado |
400 W
(A-PFC) |
Active Power |
177 W |
6 W |
| Apparent
Power |
182 VA |
7 VA |
| Vantec iON2 |
350 W |
Active Power |
192 W |
10
W |
| Apparent Power |
277 VA |
21 VA |
| Antec TruePower 330 |
330 W |
Active Power |
195 W |
22 W |
| Apparent Power |
289 VA |
38 VA |
| Ultra
X-Connect Green UV 500W |
500 W |
Active Power |
193W |
22 W |
| Apparent Power |
307 VA |
40 VA |
| AOpen Silent Power AO400-12AHN |
400 W |
Active Power |
179W |
9 W |
| Apparent Power |
275 VA |
18 VA |
| Seasonic S12-430 |
430 W
(A-PFC) |
Active Power |
179W |
6W |
| Apparent Power |
180VA |
9VA |
| PC Power and Cooling Turbo-Cool 510 Express/SLI |
510 W
(A-PFC) |
Active Power |
200 W
|
29 W
|
| Apparent Power |
202 VA |
32 VA |
| HEC
Ace Power 580UB |
580 W |
Active Power |
183 W
|
12 W
|
| Apparent Power |
272 VA |
26 VA |
| HEC
Win 550UB |
550 W |
Active Power |
184W |
10W |
| Apparent Power |
263VA |
22VA |
| Akasa
PowerPlus AK-P550FF |
550 W
(A-PFC) |
Active Power |
194W |
38W |
| Apparent Power |
197VA |
40VA |
| AOpen
Prima Power AO700-12ALN |
700 W
(A-PFC) |
Active Power |
172W |
3W |
| Apparent Power |
181VA |
9VA |
| PC
Power & Cooling Turbo-Cool 1KW |
1000 W
(A-PFC) |
Active Power |
205W |
25W |
| Apparent Power |
207VA |
32VA |
| Seasonic S12 600 |
600 W
(A-PFC) |
Active Power |
164W |
7W |
| Apparent Power |
173VA |
9VA |
| Mushkin Enhanced XP-650 |
650 W |
Active Power |
192W |
22W |
| Apparent Power |
279VA |
43VA |
| Seasonic S12 Energy Plus SS-650HT |
650
W
(A-PFC) |
Active Power |
150W |
7W |
| Apparent
Power |
150VA |
10VA |
 Seasonic M12 700W |
700
W
(A-PFC) |
Active Power |
161W |
8W |
| Apparent
Power |
165VA |
11VA |
|
With a 120W dummy load, the Seasonic M12 700W
reaches 75% efficiency which
is very good compared to most other power supplies we've tested. The
only PSU to surpass that mark is Seasonic's S12 Energy Plus SS-650HT which had an 80% efficiency. The high efficiency of the Seasonic M12 700W means that you will have a lower overall electricity bill in the long
term. Active power under load rests at 161W, and just 8W when unloaded.
Apparent Power under load rests at just 165Volt-Amps, 11VA when unloaded.
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