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 Zalman ZM600-HP power supply. The device here that resembles a power supply
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 |
3.29V |
3.36V |
0.07V |
|
+5.0V |
4.95V |
4.99V |
0.04V |
|
+12V |
11.3V |
12V |
0.7V |
|
-12V |
11.99V |
11.99V |
0V |
|
-5.0V |
5.00V |
5.00V |
0V |
|
+5.0Vsb |
5.00V |
5.00V |
0V |
We were very surprised by the amount of jitter that the motherboard read.
Let's check out what the multimeter 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 |
3.3V |
3.3V |
0V |
|
+5.0V |
4.9V |
5.0V |
0.1V |
|
+12V |
11.98V |
11.98V |
0V |
Results using the multimeter look a lot more
stable, the Zalman ZM600-HP power supply puts on a better show here.
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 |
| Corsair HX620W |
620 W
(A-PFC) |
Active Power |
171W |
8W |
| Apparent
Power |
173VA |
12VA |
 Zalman ZM600-HP |
600 W
(A-PFC) |
Active Power |
173W |
5W |
| Apparent Power |
175VA |
9VA | |
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