ASUS U-65GA 650 W Power Supply Review
Load Tests
Contents
We conducted several tests with this power supply, as described in the article Hardware Secrets Power Supply Test Methodology.
First we tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching how the reviewed unit behaved under each load. In the table below we list the load patterns we used and the results for each load.
If you add all the power listed for each test, you may find a different value than what is posted under “Total” below. Since each output can vary slightly (e.g., the +5 V output working at +5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. On the “Total” row we are using the real amount of power being delivered, as measured by our load tester.
The +12V1 and +12V2 inputs listed below are the two +12 V independent inputs from our load tester and during all tests the +12V1 input was connected to the power supply +12V1 and +12V3
rails while the +12V2 input was connected to the power supply +12V2 rail.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12V1 | 5 A (60 W) | 10 A (120 W) | 15 A (180 W) | 16 A (192 W) | 18 A (216 W) |
| +12V2 | 5 A (60 W) | 10 A (120 W) | 15 A (180 W) | 16 A (192 W) | 18 A (216 W) |
| +5V | 1 A (5 W) | 2 A (10 W) | 4 A (20 W) | 16 A (80 W) | 25 A (125 W) |
| +3.3 V | 1 A (3.3 W) | 2 A (6.6 W) | 4 A (13.2 W) | 16 A (52.8 W) | 25 A (82.5 W) |
| +5VSB | 1 A (5 W) | 1 A (5 W) | 1.5 A (7.5 W) | 2 A (10 W) | 2.5 A (12.5 W) |
| -12 V | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) |
| Total | 140.2 W | 269.0 W | 396.0 W | 531.9 W | 653.8 W |
| % Max Load | 21.6% | 41.4% | 60.9% | 81.8% | 100.6% |
| Room Temp. | 44.6° C | 44.8° C | 45.9° C | 48.6° C | 49.4° C |
| PSU Temp. | 47.3° C | 47.2° C | 47.6° C | 49.7° C | 57.1° C |
| Voltage Stability | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 167.7 W | 314.7 W | 468.3 W | 661.0 W | 863.0 W |
| Efficiency | 83.6% | 85.5% | 84.6% | 80.5% | 75.8% |
| AC Voltage | 112.9 V | 111.0 V | 109.7 V | 109.0 V | 104.9 V |
| Power Factor | 0.990 | 0.996 | 0.997 | 0.997 | 0.998 |
| Final Result | Pass | Pass | Pass | Pass | Pass |
ASUS U-65G would not turn on if we tried to pull more than 18 A from each +12 V input from our load tester. With the over current protection configured so tight, we had to use a different load pattern for tests four and five from what we usually use. We like to test power supplies pulling more current/power from its +12 V outputs, since this reflects a modern PC (as the video card and the CPU, which are the components that most consume power in the computer, are fed from these outputs). But due to this limitation, we had to increase a lot current on +5 V and +3.3 V outputs in order to achieve the desired power.
The reviewed power supply could really deliver 650 W at 49° C, but with the limitation explained above.
With the 500 W power supply from ASUS we had a problem where the unit could not deliver efficiency above 80% in most scenarios. With U-65GA, however, you will see efficiency below 80% only when you try to pull its full labeled power. If you pull between 40% and 60% (260 W and 390 W) from its labeled power, you will achieve an excellent efficiency of 85%. At 20% load (130 W) efficiency is still very good, at 83.6%. At 80% load (520 W) efficiency drops to 81.8%, but still above the 80% mark.
This unit is 80 Plus-certified, but you need to keep in mind that this organization tests power supplies at 23° C (a temperature that is too low in our opinion), while we tested this power supply at 49.4° C. The higher the temperature, the lower efficiency is.
Voltage regulation was one of the highlights from U-65GA, with all voltages within 3% from their nominal values, i.e., closer to their nominal values than required, as the ATX specification allows voltages to be up to 5% from their nominal values. This includes -12 V, an output that usually doesn’t like to stay so close to its nominal value.
Noise and ripple levels stayed inside the allowed range (up to 120 mV for +12 V and up to 50 mV for +5 V and +3.3 V, peak-to-peak), however higher than we’d like to see.
Figure 15: +12V1 input from load tester at 653.8 W (67.4 mV).
Figure 16: +5V rail with power supply delivering 653.8 W (25.8 mV).
Figure 17: +3.3 V rail with power supply delivering 653.8 W (32.8 mV).
Let’s see if we could pull more than 650 W from the reviewed unit.