Why you can trust Tom's Hardware Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.
To learn more about our PSU tests and methodology, please check out How We Test Power Supply Units.
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.
The load regulation is tight enough on all rails but 5VSB.
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 is long and the power-ok signal is accurate.
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 with 115V input is quite high, while with 230V is at normal levels, for a 750W PSU equipped with the proper bulk cap.
10-110% Load Tests
These tests reveal the V750's load regulation and efficiency levels under high ambient temperatures. They also show how the fan speed profile behaves under increased operating temperatures.
| Test # | 12V | 5V | 3.3V | 5VSB | DC/AC (Watts) | Efficiency | Fan Speed (RPM) | PSU Noise (dB[A]) | Temps (In/Out) | PF/AC Volts |
| 1 | 4.317A | 1.961A | 1.971A | 0.997A | 74.461 | 84.964% | 0 | <6.0 | 42.86°C | 0.966 |
| 12.246V | 5.096V | 3.350V | 5.014V | 87.638 | 39.09°C | 115.12V | ||||
| 2 | 9.688A | 2.928A | 2.937A | 1.201A | 149.351 | 89.427% | 0 | <6.0 | 43.86°C | 0.991 |
| 12.227V | 5.122V | 3.370V | 4.997V | 167.009 | 39.81°C | 115.12V | ||||
| 3 | 15.470A | 3.421A | 3.421A | 1.406A | 224.860 | 90.524% | 0 | <6.0 | 45.18°C | 0.992 |
| 12.208V | 5.116V | 3.361V | 4.981V | 248.398 | 40.77°C | 115.11V | ||||
| 4 | 21.101A | 3.922A | 3.940A | 1.612A | 299.679 | 90.129% | 1583 | 40.9 | 41.87°C | 0.994 |
| 12.249V | 5.100V | 3.352V | 4.965V | 332.500 | 47.41°C | 115.11V | ||||
| 5 | 26.358A | 4.920A | 4.936A | 1.819A | 374.576 | 90.216% | 1616 | 41.5 | 42.40°C | 0.996 |
| 12.295V | 5.082V | 3.342V | 4.950V | 415.200 | 48.59°C | 115.11V | ||||
| 6 | 31.734A | 5.915A | 5.896A | 2.028A | 449.498 | 89.990% | 1677 | 42.1 | 42.73°C | 0.996 |
| 12.280V | 5.073V | 3.357V | 4.933V | 499.500 | 49.79°C | 115.11V | ||||
| 7 | 37.165A | 6.866A | 6.902A | 2.239A | 524.826 | 89.541% | 1754 | 43.1 | 43.00°C | 0.997 |
| 12.262V | 5.098V | 3.347V | 4.915V | 586.128 | 51.28°C | 115.11V | ||||
| 8 | 42.610A | 7.862A | 7.913A | 2.450A | 600.126 | 88.989% | 1805 | 43.9 | 43.63°C | 0.997 |
| 12.244V | 5.089V | 3.336V | 4.899V | 674.382 | 52.61°C | 115.11V | ||||
| 9 | 48.435A | 8.363A | 8.357A | 2.452A | 674.666 | 88.390% | 1858 | 44.6 | 44.24°C | 0.997 |
| 12.226V | 5.082V | 3.350V | 4.895V | 763.286 | 54.06°C | 115.11V | ||||
| 10 | 54.083A | 8.870A | 8.885A | 3.094A | 749.902 | 87.621% | 1902 | 45.3 | 45.99°C | 0.997 |
| 12.207V | 5.074V | 3.343V | 4.849V | 855.847 | 56.32°C | 115.11V | ||||
| 11 | 60.340A | 8.883A | 8.907A | 3.097A | 825.135 | 86.844% | 1929 | 45.7 | 46.67°C | 0.997 |
| 12.188V | 5.067V | 3.334V | 4.845V | 950.136 | 58.48°C | 115.11V | ||||
| CL1 | 0.143A | 16.004A | 16.000A | 0.000A | 138.568 | 82.764% | 1694 | 42.3 | 42.04°C | 0.992 |
| 12.219V | 5.142V | 3.408V | 5.069V | 167.425 | 48.66°C | 115.13V | ||||
| CL2 | 62.013A | 1.002A | 1.000A | 1.000A | 770.290 | 88.162% | 1869 | 44.8 | 45.81°C | 0.997 |
| 12.207V | 5.019V | 3.280V | 4.987V | 873.717 | 56.63°C | 115.11V |
The PSU operates in passive mode up to the 30% load test, but in the next test, the fan spins at high speed, exceeding 40 dB(A). Moreover, the efficiency levels meet the 80 PLUS Gold standard's requirements, despite the high operating temperatures, and the PF readings are high, even at light loads.
20-80W Load Tests
In the following tests, we measure the V750'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.
| Test # | 12V | 5V | 3.3V | 5VSB | DC/AC (Watts) | Efficiency | Fan Speed (RPM) | PSU Noise (dB[A]) | PF/AC Volts |
| 1 | 1.174A | 0.490A | 0.476A | 0.198A | 19.493 | 68.155% | 0 | <6.0 | 0.828 |
| 12.261V | 5.098V | 3.359V | 5.065V | 28.601 | 115.11V | ||||
| 2 | 2.418A | 0.980A | 0.983A | 0.396A | 39.927 | 79.120% | 0 | <6.0 | 0.921 |
| 12.256V | 5.096V | 3.355V | 5.052V | 50.464 | 115.11V | ||||
| 3 | 3.592A | 1.472A | 1.459A | 0.595A | 59.391 | 83.446% | 0 | <6.0 | 0.955 |
| 12.250V | 5.095V | 3.352V | 5.039V | 71.173 | 115.12V | ||||
| 4 | 4.838A | 1.963A | 1.968A | 0.796A | 79.832 | 85.849% | 0 | <6.0 | 0.971 |
| 12.245V | 5.094V | 3.349V | 5.026V | 92.991 | 115.12V |
The efficiency at light loads is not that high. With 20W load, it should be 70%, at least, and exceed 80% with 40W.
2% or 10W Load Test
Intel plans on raising the ante at efficiency levels under ultra-light loads. So from July 2020, the ATX spec will require 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.
| Test # | 12V | 5V | 3.3V | 5VSB | DC/AC (Watts) | Efficiency | Fan Speed (RPM) | PSU Noise (dB[A]) | PF/AC Volts |
| 1 | 1.044A | 0.263A | 0.264A | 0.051A | 15.289 | 63.901% | 0 | <6.0 | 0.792 |
| 12.268V | 5.078V | 3.359V | 5.075V | 23.926 | 115.11V |
It is nice to see over 60% with 2% of the PSU's max-rated-capacity. Still the ATX asks for more than 70%.
Efficiency
Next, we plotted a chart showing the V750’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 efficiency levels are close to the middle of the pack in all three load regions (super light, light, and normal).
5VSB Efficiency
| Test # | 5VSB | DC/AC (Watts) | Efficiency | PF/AC Volts |
| 1 | 0.100A | 0.508 | 71.148% | 0.097 |
| 5.076V | 0.714 | 115.08V | ||
| 2 | 0.250A | 1.266 | 77.479% | 0.185 |
| 5.066V | 1.634 | 115.08V | ||
| 3 | 0.550A | 2.777 | 79.662% | 0.269 |
| 5.049V | 3.486 | 115.08V | ||
| 4 | 1.000A | 5.023 | 79.680% | 0.317 |
| 5.023V | 6.304 | 115.08V | ||
| 5 | 1.500A | 7.490 | 79.647% | 0.342 |
| 4.994V | 9.404 | 115.08V | ||
| 6 | 2.999A | 14.697 | 78.699% | 0.378 |
| 4.900V | 18.675 | 115.08V |
The 5VSB rail has satisfactory efficiency levels.
Power Consumption In Idle And Standby
| Mode | 12V | 5V | 3.3V | 5VSB | Watts | PF/AC Volts |
| Idle | 12.291V | 5.074V | 3.361V | 5.080V | 7.119 | 0.456 |
| 115.1V | ||||||
| Standby | 0.079 | 0.011 | ||||
| 115.1V |
The energy consumption is low enough with 115V input, and quite high with 230V.
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).
Under high operating temperatures, the fan profile is aggressive.
The following results were obtained at 30 to 32 degrees Celsius (86 to 89.6 degrees Fahrenheit) ambient temperature.
As you can see in the graphs above, the passive operation is limited not only by the load at +12V but also by the load on the minor rails. With 310W and higher loads, the fan enters the 35-40 dB(A) zone while with more than 540W at +12V, it exceeds 40 dB(A).
MORE: Best Power Supplies
MORE: How We Test Power Supplies
MORE: All Power Supply Content
