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.
Load Regulation, Hold-Up Time & Inrush Current
To learn more about our PSU tests and methodology, please check out How We Test Power Supply Units.
Primary Rails And 5VSB Load Regulation
Load Regulation testing is detailed here.
Hold-Up Time
Our hold-up time tests are described in detail here.
The hold-up time we measure is over 17ms, though the power-good signal doesn't satisfy the ATX specification's 16ms limit. At least it's accurate.
Inrush Current
For details on our inrush current testing, please click here.
Measured inrush current is on the high side with both voltage inputs.
Load Regulation And Efficiency Measurements
The first set of tests reveals the stability of the voltage rails and the GX-F750's efficiency. The applied load equals (approximately) 10 to 110 percent of the PSU's maximum load in increments of 10 percentage points.
We conducted two additional tests. During the first, we stressed the two minor rails (5V and 3.3V) with a high load, while the load at +12V was only 0.1A. This test reveals whether a PSU is compatible with Intel's C6/C7 sleep states or not. In the second test, we determined the maximum load the +12V rail could handle with minimal load on the minor rails.
| Test # | 12V | 5V | 3.3V | 5VSB | DC/AC (Watts) | Efficiency | Fan Speed | PSU Noise | Temps (In/Out) | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 4.393A | 2.004A | 1.980A | 0.981A | 74.787 | 84.018% | 810 RPM | 23.3 dB(A) | 31.80°C | 0.974 |
| 12.111V | 4.984V | 3.333V | 5.092V | 89.013 | 36.73°C | 115.07V | ||||
| 2 | 9.840A | 3.011A | 2.975A | 1.181A | 149.806 | 88.902% | 830 RPM | 24.4 dB(A) | 32.46°C | 0.979 |
| 12.087V | 4.976V | 3.324V | 5.080V | 168.507 | 37.54°C | 115.07V | ||||
| 3 | 15.637A | 3.517A | 3.495A | 1.380A | 224.871 | 90.191% | 885 RPM | 26.3 dB(A) | 33.19°C | 0.979 |
| 12.074V | 4.969V | 3.318V | 5.071V | 249.328 | 39.52°C | 115.06V | ||||
| 4 | 21.436A | 4.030A | 3.984A | 1.580A | 299.773 | 90.485% | 970 RPM | 29.4 dB(A) | 33.78°C | 0.984 |
| 12.063V | 4.963V | 3.312V | 5.060V | 331.297 | 41.87°C | 115.04V | ||||
| 5 | 26.907A | 5.041A | 4.991A | 1.781A | 374.744 | 90.305% | 1070 RPM | 31.5 dB(A) | 34.79°C | 0.988 |
| 12.052V | 4.955V | 3.304V | 5.049V | 414.976 | 43.55°C | 115.06V | ||||
| 6 | 32.384A | 6.068A | 6.006A | 1.982A | 449.741 | 89.851% | 1170 RPM | 33.9 dB(A) | 35.49°C | 0.991 |
| 12.041V | 4.948V | 3.296V | 5.038V | 500.543 | 45.17°C | 115.07V | ||||
| 7 | 37.840A | 7.083A | 7.021A | 2.186A | 524.667 | 88.818% | 1265 RPM | 36.9 dB(A) | 36.04°C | 0.992 |
| 12.040V | 4.940V | 3.289V | 5.028V | 590.720 | 46.69°C | 115.08V | ||||
| 8 | 43.326A | 8.114A | 8.043A | 2.391A | 599.654 | 88.095% | 1390 RPM | 38.5 dB(A) | 36.94°C | 0.994 |
| 12.031V | 4.931V | 3.282V | 5.015V | 680.691 | 49.54°C | 115.07V | ||||
| 9 | 49.246A | 8.632A | 8.580A | 2.396A | 674.698 | 87.371% | 1490 RPM | 40.5 dB(A) | 38.49°C | 0.995 |
| 12.023V | 4.925V | 3.275V | 5.009V | 772.222 | 52.29°C | 115.09V | ||||
| 10 | 54.918A | 9.154A | 9.086A | 3.006A | 749.546 | 86.443% | 1545 RPM | 42.2 dB(A) | 39.35°C | 0.995 |
| 12.015V | 4.918V | 3.268V | 4.988V | 867.098 | 53.62°C | 115.08V | ||||
| 11 | 61.205A | 9.166A | 9.102A | 3.009A | 824.474 | 85.723% | 1550 RPM | 42.7 dB(A) | 40.42°C | 0.996 |
| 12.005V | 4.911V | 3.263V | 4.983V | 961.786 | 55.32°C | 115.06V | ||||
| CL1 | 0.100A | 18.030A | 18.002A | 0.004A | 149.901 | 84.143% | 1190 RPM | 34.7 dB(A) | 38.30°C | 0.978 |
| 12.078V | 4.948V | 3.303V | 5.097V | 178.151 | 47.96°C | 115.04V | ||||
| CL2 | 61.948A | 1.002A | 1.005A | 1.002A | 758.165 | 86.878% | 1535 RPM | 41.8 dB(A) | 39.92°C | 0.995 |
| 12.024V | 4.936V | 3.284V | 5.045V | 872.677 | 53.54°C | 115.06V |
The load regulation on all rails is satisfactory. However, it still falls short of this category's top performers. As for the 80 PLUS Gold certification, this PSU satisfies the 20% and 50% load efficiency requirements, but doesn't quite get there under full load. To be fair, this is fairly normal since we test at a much higher temperature than the 80 PLUS organization.
When it comes to noise, the fan spins at 810 RPM under just 75W of load. That's pretty high for such a low load level. It also exceeds 1000 RPM with 50% load, surpassing the 30 dB(A) mark. As mentioned, the fan profile is a bit aggressive. Cougar should relax it a bit in future versions of this PSU.
We we were also troubled by the problems we encountered trying to make the GX-F750 deliver its full capacity at 45°C. Cougar states that this model is rated for continuous full load delivery at 50°C. However, we cannot confirm those claims. In our effort to make the PSU deliver full power or more in our 110% load test at temperatures close to 45°C, we broke the first sample after ignoring its over-temperature protection warnings. So, we decided to be extra gentle with the second one and stay close to 40°C.
[Update, 4/18/2018: Cougar sent us a new sample which doesn't have a problem delivering more than its full power at over 45°C ambient]
MORE: Best Power Supplies
MORE: How We Test Power Supplies
MORE: All Power Supply Content
