Gigabyte UD750GM Power Supply Review

Decent, efficient, and with a reasonable price tag.

Gigabyte UD750GM
(Image: © Tom's Hardware)

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Primary Rails And 5VSB Load Regulation

The following charts show the main rails' voltage values recorded between a range of 40W up to the PSU's maximum specified load, along with the deviation (in percent). Tight regulation is an important consideration every time we review a power supply because it facilitates constant voltage levels despite varying loads. Tight load regulation also, among other factors, improves the system’s stability, especially under overclocked conditions and, at the same time, it applies less stress to the DC-DC converters that many system components utilize.

Load regulation is tight at 12V, tight enough at 5V, and loose at 3.3V. 

Hold-Up Time

Put simply, hold-up time is the amount of time that the system can continue to run without shutting down or rebooting during a power interruption.

The hold-up time meets the ATX spec's requirement of 17 ms and the power ok signal is accurate and longer than 16 ms. 

Inrush Current

Inrush current, or switch-on surge, refers to the maximum, instantaneous input current drawn by an electrical device when it is first turned on. A large enough inrush current can cause circuit breakers and fuses to trip. It can also damage switches, relays, and bridge rectifiers. As a result, the lower the inrush current of a PSU right as it is turned on, the better.

The inrush current is low with 115V, but pretty high with 230V. 

Leakage Current

In layman's terms, leakage current is the unwanted transfer of energy from one circuit to another. In power supplies, it is the current flowing from the primary side to the ground or the chassis, which in the majority of cases is connected to the ground. For measuring leakage current, we use a GW Instek GPT-9904 electrical safety tester instrument.

The leakage current test is conducted at 110% of the DUT's rated voltage input (so for a 230-240V device, we should conduct the test with 253-264V input). The maximum acceptable limit of a leakage current is 3.5 mA and it is defined by the IEC-60950-1 regulation, ensuring that the current is low and will not harm any person coming in contact with the power supply's chassis.

Gigabyte UD750GM

(Image credit: Tom's Hardware)

Leakage current is low. 

10-110% Load Tests

These tests reveal the PSU's load regulation and efficiency levels under high ambient temperatures. They also show how the fan speed profile behaves under increased operating temperatures.

Swipe to scroll horizontally
Test12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])Temps (In/Out)PF/AC Volts
10%4.416A1.951A1.954A0.987A75.00386.284%0<6.045.13°C0.954
Row 2 - Cell 0 12.094V5.126V3.378V5.064V86.93Row 2 - Cell 6 Row 2 - Cell 7 Row 2 - Cell 8 40.54°C115.1V
20%9.845A2.93A2.939A1.187A149.94889.733%0<6.046.07°C0.972
Row 4 - Cell 0 12.092V5.119V3.368V5.054V167.102Row 4 - Cell 6 Row 4 - Cell 7 Row 4 - Cell 8 40.7°C115.08V
30%15.629A3.421A3.434A1.387A224.95391.127%94327.941.26°C0.98
Row 6 - Cell 0 12.087V5.116V3.364V5.047V246.853Row 6 - Cell 6 Row 6 - Cell 7 Row 6 - Cell 8 47.08°C115.06V
40%21.430A3.915A3.935A1.588A300.05691.602%95028.241.54°C0.984
Row 8 - Cell 0 12.079V5.109V3.354V5.038V327.559Row 8 - Cell 6 Row 8 - Cell 7 Row 8 - Cell 8 47.64°C115.04V
50%26.851A4.899A4.933A1.79A374.61291.384%95828.342.17°C0.985
Row 10 - Cell 0 12.071V5.103V3.345V5.028V409.937Row 10 - Cell 6 Row 10 - Cell 7 Row 10 - Cell 8 48.69°C115.02V
60%32.307A5.887A5.937A1.993A449.56390.95%125034.442.85°C0.987
Row 12 - Cell 0 12.064V5.097V3.335V5.018V494.299Row 12 - Cell 6 Row 12 - Cell 7 Row 12 - Cell 8 49.94°C115V
70%37.769A6.877A6.944A2.197A524.4790.32%170141.143.62°C0.987
Row 14 - Cell 0 12.056V5.09V3.327V5.009V580.68Row 14 - Cell 6 Row 14 - Cell 7 Row 14 - Cell 8 51.13°C114.98V
80%43.303A7.871A7.954A2.3A599.66389.743%195544.543.73°C0.988
Row 16 - Cell 0 12.049V5.084V3.319V5.001V668.196Row 16 - Cell 6 Row 16 - Cell 7 Row 16 - Cell 8 52.06°C114.96V
90%49.173A8.372A8.454A2.403A674.62189.225%198544.844.76°C0.989
Row 18 - Cell 0 12.042V5.077V3.312V4.995V756.082Row 18 - Cell 6 Row 18 - Cell 7 Row 18 - Cell 8 54.04°C114.93V
100%54.852A8.876A8.994A3.014A749.81888.446%197244.645.43°C0.986
Row 20 - Cell 0 12.034V5.07V3.302V4.977V847.773Row 20 - Cell 6 Row 20 - Cell 7 Row 20 - Cell 8 55.52°C114.91V
110%60.401A9.883A10.095A3.017A824.76987.771%198644.846.66°C0.986
Row 22 - Cell 0 12.028V5.059V3.298V4.972V939.669Row 22 - Cell 6 Row 22 - Cell 7 Row 22 - Cell 8 57.51°C114.89V
CL10.115A12.337A12.417A0A106.28683.897%0<6.048.72°C0.967
Row 24 - Cell 0 12.090V5.123V3.357V5.073V126.683Row 24 - Cell 6 Row 24 - Cell 7 Row 24 - Cell 8 42.25°C115.09V
CL20.115A19.539A0A0A101.39982.618%0<6.050.53°C0.966
Row 26 - Cell 0 12.092V5.119V3.366V5.078V122.736Row 26 - Cell 6 Row 26 - Cell 7 Row 26 - Cell 8 43.17°C115.09V
CL30.115A0A19.702A0A67.37777.141%0<6.052.61°C0.955
Row 28 - Cell 0 12.090V5.114V3.349V5.075V87.34Row 28 - Cell 6 Row 28 - Cell 7 Row 28 - Cell 8 44.52°C115.1V
CL462.269A0A0A0A749.5589.433%199444.845.74°C0.99
Row 30 - Cell 0 12.037V5.062V3.324V5.048V838.103Row 30 - Cell 6 Row 30 - Cell 7 Row 30 - Cell 8 55.85°C114.91V

We pushed hard this PSU during these tests, but it didn't budge. 

20-80W Load Tests

In the following tests, we measure the PSU's efficiency at loads significantly lower than 10% of its maximum capacity (the lowest load the 80 Plus standard measures). This is important for representing when a PC is idle with power-saving features turned on.

Swipe to scroll horizontally
Test12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])Temps (In/Out)PF/AC Volts
20W1.228A0.488A0.487A0.197A20.00169.932%0<6.040.09°C0.876
Row 2 - Cell 0 12.097V5.123V3.385V5.085V28.606Row 2 - Cell 6 Row 2 - Cell 7 Row 2 - Cell 8 37.04°C115.12V
40W2.704A0.683A0.683A0.295A40.00281.058%0<6.040.71°C0.926
Row 4 - Cell 0 12.086V5.121V3.383V5.082V49.349Row 4 - Cell 6 Row 4 - Cell 7 Row 4 - Cell 8 37.45°C115.11V
60W4.180A0.879A0.878A0.394A60.00185.662%0<6.042.23°C0.946
Row 6 - Cell 0 12.090V5.12V3.382V5.078V70.042Row 6 - Cell 6 Row 6 - Cell 7 Row 6 - Cell 8 38.48°C115.11V
80W5.650A1.074A1.074A0.493A79.95287.795%0<6.044.03°C0.956
Row 8 - Cell 0 12.093V5.122V3.38V5.075V91.063Row 8 - Cell 6 Row 8 - Cell 7 Row 8 - Cell 8 39.98°C115.1V

Despite the high operating temperatures, the PSU's fan didn't engage in these tests because of the low thermal loads. 

2% or 10W Load Test

From July 2020, the ATX spec requires 70% and higher efficiency with 115V input. The applied load is only 10W for PSUs with 500W and lower capacities, while for stronger units, we dial 2% of their max-rated capacity.

Swipe to scroll horizontally
12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])Temps (In/Out)PF/AC Volts
1.072A0.223A0.223A0.053A15.1266.991%0<6.026.7°C0.86
Row 2 - Cell 0 12.087V5.121V3.387V5.09V22.579Row 2 - Cell 6 Row 2 - Cell 7 23.74°C115.11V

With only 2% of its max-rated capacity, the platform delivers over 60% efficiency. 

Efficiency & Power Factor

Next, we plotted a chart showing the PSU's efficiency at low loads and loads from 10 to 110% of its maximum rated capacity. The higher a PSU’s efficiency, the less energy goes wasted, leading to a reduced carbon footprint and lower electricity bills. The same goes for Power Factor.

Efficiency is high with normal loads, but it drops with lighter loads. 

5VSB Efficiency

Swipe to scroll horizontally
Test #5VSBDC/AC (Watts)EfficiencyPF/AC Volts
10.1A0.509W74.356%0.092
Row 2 - Cell 0 5.09V0.685WRow 2 - Cell 3 115.12V
20.25A1.272W78.671%0.193
Row 4 - Cell 0 5.087V1.617WRow 4 - Cell 3 115.12V
30.55A2.795W80.059%0.318
Row 6 - Cell 0 5.081V3.491WRow 6 - Cell 3 115.12V
41A5.072W80.616%0.404
Row 8 - Cell 0 5.072V6.291WRow 8 - Cell 3 115.12V
51.5A7.593W80.853%0.442
Row 10 - Cell 0 5.061V9.391WRow 10 - Cell 3 115.12V
63A15.092W78.882%0.496
Row 12 - Cell 0 5.03V19.132WRow 12 - Cell 3 115.12V

The 5VSB rail is efficient. 

Power Consumption In Idle And Standby

Swipe to scroll horizontally
Mode12V5V3.3V5VSBWattsPF/AC Volts
Idle12.092V5.122V3.393V5.092V7.9630.624
Row 2 - Cell 0 Row 2 - Cell 1 Row 2 - Cell 2 Row 2 - Cell 3 Row 2 - Cell 4 Row 2 - Cell 5 115.12V
StandbyRow 3 - Cell 1 Row 3 - Cell 2 Row 3 - Cell 3 0.0340.007
Row 4 - Cell 0 Row 4 - Cell 1 Row 4 - Cell 2 Row 4 - Cell 3 Row 4 - Cell 4 Row 4 - Cell 5 115.12V

Vampire power should be lower with 230V input. 

Fan RPM, Delta Temperature, And Output Noise

All results are obtained between an ambient temperature of 37 to 47 degrees Celsius (98.6 to 116.6 degrees Fahrenheit).

(Image credit: Tom's Hardware)

(Image credit: Tom's Hardware)

The fan speed profile gets aggressive with high loads and increased operating temperatures, to protect the mediocre quality filtering caps on the secondary side, 

The following results were obtained at 30 to 32 degrees Celsius (86 to 89.6 degrees Fahrenheit) ambient temperature.       

(Image credit: Tom's Hardware)

(Image credit: Tom's Hardware)

At normal operating temperatures, close to 30 degrees Celsius, the PSU's passive operation doesn't last long, especially if you apply high loads on the minor rails. For the most part, the cooling fan's noise is in the 25-30 dBA range, which is acceptable, and with 550W and higher loads, it exceeds 30 dBA. With 580W, the noise goes over 35 dBA, and with anything above 650W, the PSU's noise exceeds 40 dBA. 

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Aris Mpitziopoulos
Contributing Editor

Aris Mpitziopoulos is a contributing editor at Tom's Hardware, covering PSUs.

  • PiranhaTech
    I'm curious if you did the GamersNexus tests. A lot of PC builders are going to wait for their tests before considering a Gigabyte PSU due to the exploding PSU issue they had

    aACtT_rzToIView: https://www.youtube.com/watch?v=aACtT_rzToI
    Reply