All measurements were performed using two Chroma 6314A mainframes equipped with the following electronic loads: six 63123A [350 W each], one 63102A [100 W x2], and one 63101A [200 W]. The aforementioned equipment is able to deliver 2500 W of load, and all loads are controlled by a custom-made software. We also used a Picoscope 3424 oscilloscope, a Picotech TC-08 thermocouple data logger, a Fluke 175 multimeter, and a Yokogawa WT210 power meter. We also included a wooden box, which, along with some heating elements, was used as a hot box. Finally, we had at our disposal four more oscilloscopes (Rigol 1052E and VS5042, Stingray DS1M12, a second Picoscope 3424), and a CEM DT-8852 sound level meter. In this article, you will find more details about our equipment and the review methodology we follow. Finally, we conduct all of our tests at 40-45°C ambient in order to simulate with higher accuracy the environment seen inside a typical system, with 40-45°C being derived from a standard ambient assumption of 23°C and 17-22°C being added for the typical temperature rise within a system.
Primary Rails Voltage Regulation
The following charts show the voltage values of the main rails, recorded over a range from 60W to the maximum specified load, and the deviation (in percent) for the same load range.
5VSB Regulation
The following chart shows how the 5VSB rail deals with the load we throw at it.
Hold-up Time
The hold-up time is a very important characteristic of a PSU and represents the amount of time, usually measured in milliseconds, that a PSU can maintain output regulations as defined by the ATX spec without input power. In other words, it is the amount of time that the system can continue to run without shutting down or rebooting during a power interruption. The ATX spec sets the minimum hold-up time to 16 ms with the maximum continuous output load. In the following screenshot, the blue line is the mains signal and the yellow line is the "Power Good" signal. The latter is de-asserted to a low state when any of the +12V, 5V, or 3.3V output voltages fall below the undervoltage threshold, or after the mains power has been removed for a sufficiently long time to guarantee that the PSU cannot operate anymore.
As you can see from the above scope shot, the PSU failed to reach the minimum allowed time that the ATX spec requires. Its failure is thankfully minor as it registered a time that is only 2 ms lower than the limit; that said, it is still a fail.
Inrush Current
Inrush current or switch-on surge refers to the maximum, instantaneous input-current drawn by an electrical device when first turned on. Because of the charging current of the APFC capacitor(s), PSUs produce large inrush-current right as they are turned on. Large inrush current can cause the tripping of circuit breakers and fuses and may also damage switches, relays, and bridge rectifiers; as a result, the lower the inrush current of a PSU right as they are turned on, the better.
The inrush current that the PSU registered is close to the average of the category (750 W units), so it is good enough.
Voltage Regulation and Efficiency Measurements
The first set of tests revealed the stability of the voltage rails and the efficiency of the HCG-750M. The applied load was equal to (approximately) 20%, 40%, 50%, 60%, 80%, 100%, and 110% of the maximum load that the PSU can handle. We conducted two additional tests. In the first test, we stressed the two minor rails (5V and 3.3V) with a high load while the load at +12V was only 0.10 A. This test reveals whether the PSU is Haswell ready or not. In the second test, we dialed the maximum load that the +12V rail could handle while the load on the minor rails was minimal.
Voltage Regulation & Efficiency Testing Data Antec HCG-750M
Test
12 V
5 V
3.3 V
5VSB
Power (DC/AC)
Efficiency
Fan Speed
Fan Noise
Temp (In/Out)
PF/AC Volts
20% Load
10.501A
1.961A
1.964A
0.980A
149.72W
85.74%
1505 RPM
44.6 dBA
39.58°C
0.932
12.206V
5.083V
3.358V
5.088V
174.62W
45.95°C
230.1V
40% Load
21.390A
3.940A
3.949A
1.179A
299.70W
88.11%
1975 RPM
51.7 dBA
41.67°C
0.959
12.182V
5.065V
3.341V
5.070V
340.15W
48.35°C
230.1V
50% Load
26.723A
4.943A
4.948A
1.580A
374.69W
88.13%
2183 RPM
53.6 dBA
42.54°C
0.967
12.170V
5.057V
3.333V
5.053V
425.17W
49.79°C
230.1V
60% Load
32.070A
5.937A
5.954A
1.984A
449.59W
87.98%
2204 RPM
53.8 dBA
43.36°C
0.970
12.156V
5.048V
3.323V
5.037V
511.04W
51.74°C
230.0V
80% Load
42.959A
7.946A
7.982A
2.391A
599.43W
87.50%
2230 RPM
54.0 dBA
44.30°C
0.978
12.130V
5.029V
3.307V
5.012V
685.10W
56.08°C
229.9V
100% Load
54.519A
8.975A
9.018A
3.006A
749.32W
86.62%
2230 RPM
54.0 dBA
44.54°C
0.983
12.100V
5.012V
3.291V
4.984V
865.05W
59.42°C
229.9V
110% Load
60.783A
8.989A
9.042A
3.011A
824.17W
86.18%
2230 RPM
54.0 dBA
45.83°C
0.984
12.084V
5.005V
3.284V
4.977V
956.30W
62.74°C
229.9V
Crossload 1
0.081A
18.013A
18.002A
0.004A
151.85W
80.43%
2204 RPM
53.8 dBA
42.67°C
0.936
12.191V
5.047V
3.329V
5.083V
188.80W
50.16°C
230.2V
Crossload 2
61.950A
1.000A
1.003A
1.002A
763.24W
86.98%
2230 RPM
54.0 dBA
44.89°C
0.983
12.104V
5.030V
3.309V
5.038V
877.50W
59.61°C
229.9V
Voltage regulation on all rails is good and the +12V rail registered the tightest of all with a deviation under 1%. It is impressive to see a mid-category PSU meet the high-end competition eye to eye in +12V voltage regulation performance, especially as +12V is the most important rail of all. The HCG-750M also had absolutely no problem delivering its full power and even more at high operating temperatures close to 45°C. That said, the fan had to spin up to full speed to move the heat out of the PSU's internals under those conditions. The Delta difference between input and output even reached 17°C with the 110% of maximum-rated-capacity load! This very large Delta difference means two things: The fan does a hell of a job and the unit's thermal dissipation at high loads is large. For a Bronze unit, efficiency is fairly good throughout all the loads we dialed in the above tests.