CWT 750VH 750 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. Then we tried to pull even more power from this unit and the results for this test are in the next page.
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.
+12V2 is the second +12V input from our load tester and during our tests we connected the power supply EPS12V connector to it, which is connected to the power supply +12V1 and +12V2 rails. The +12V1 input from our load tester was connected to the +12V3 (main motherboard cable), +12V4 (peripheral connectors) and +12V2 (video card auxiliary cable) rails at the same time.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12V1 | 5 A (60 W) | 11 A (132 W) | 17 A (204 W) | 24 A (288 W) | 33 A (396 W) |
| +12V2 | 5 A (60 W) | 10 A (120 W0 | 15 A (180 W) | 20 A (240 W0 | 22 A (264 W) |
| +5V | 2 A (10 W) | 4 A (20 W) | 6 A (30 W) | 8 A (40 W) | 8 A (40 W) |
| +3.3 V | 2 A (6.6 W) | 4 A (13.2 W) | 6 A (19.8 W) | 8 A (26.4 W) | 8 A (26.4 W) |
| +5VSB | 1 A (5 W) | 1 A (5 W) | 1.5 A (7.5 W) | 2 A (10 W) | 2 A (15 W) |
| -12 V | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.8 A (9.6 W) |
| Total | 149.5 W | 299.4 W | 450.8 W | 613.8 W | 754.2 W |
| % Max Load | 19.9% | 39.9% | 60.1% | 81.8% | 100.6% |
| Room Temp. | 47.9° C | 47.9° C | 48.8° C | 48.6° C | 50.9° C |
| Voltage Stability | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 175.0 W | 340.0 W | 518.0 W | 717.0 W | 906.0 W |
| Efficiency | 85.4% | 88.1% | 87.0% | 85.6% | 83.2% |
| Final Result | Pass | Pass | Pass | Pass | Pass |
This power supply could not only deliver its labeled power at 50° C, but more than that (see results in the next page).
Efficiency was the highlight from this product. It could deliver at least 83% efficiency when fully loaded, peaking 88% when delivering 40% of its nominal 750 W capacity (300 W).
Ripple and noise where below the maximum allowed, even though models from some other manufacturers can deliver a lower noise level at their +12 V outputs when their units are delivering their full load. Just to remember, the maximum allowed for the +12 V outputs is 120 mV peak-to-peak and the maximum allowed for the +5 V and +3.3 V outputs is 50 mV peak-to-peak. Below you see noise levels for the reviewed power supply delivering 750 W (test number five).
Figure 15: Noise level at +12V1 input from our load tester with the reviewed unit delivering 750 W (74.2 mV).
Figure 16: Noise level at +12V2 input from our load tester with the reviewed unit delivering 750 W (83 mV).
Figure 17: Noise level at +5 V input from our load tester with the reviewed unit delivering 750 W (14.2 mV).
Figure 18: Noise level at +3.3 V input from our load tester with the reviewed unit delivering 750 W (21.6 mV).
Now let’s see how much power we could pull from this unit keeping it working inside ATX specs.