bequiet! Straight Power E9 CM 680 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 the behavior of the reviewed unit 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 powers listed for each test, you may find a different value than what is posted under “Total” below. Since each output can have a slight variation (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. In the “Total” row, we are using the real amount of power being delivered, as measured by our load tester.
The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During this test, the +12VA input was connected to the power supply +12V1 and +12V3 rails, while the +12VB input was connected to the power supply +12V2 rail.
During test five, we couldn’t pull more than 21 A from the power supply +12V2 rail, as the over current protection (OCP) kicked in. That is the reason the current distribution between the two +12 V inputs may look unbalanced in test five.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12VA | 5 A (60 W) | 10 A (120 W) | 15 A (180 W) | 20 A (240 W) | 28.5 A (342 W) |
| +12VB | 5 A (60 W) | 10 A (120 W) | 15 A (180 W) | 20 A (240 W) | 21 A (252 W) |
| +5 V | 1 A (5 W) | 2 A (10 W) | 4 A (20 W) | 6 A (30 W) | 8 A (40 W) |
| +3.3 V | 1 A (3.3 W) | 2 A (6.6 W) | 4 A (13.2 W) | 6 A (19.8 W) | 8 A (26.4 W) |
| +5VSB | 1 A (5 W) | 1.5 A (7.5 W) | 2 A (10 W) | 2.5 A (12.5 W) | 3 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) | 0.5 A (6 W) |
| Total | 137.3 W | 275.8 W | 412.3 W | 535.2 W | 678.4 W |
| % Max Load | 20.2% | 40.6% | 60.6% | 78.7% | 99.8% |
| Room Temp. | 44.9° C | 44.9° C | 46.2° C | 45.8° C | 45.6° C |
| PSU Temp. | 48.2° C | 48.6° C | 49.2° C | 49.9° C | 48.4° C |
| Voltage Regulation | Pass | Pass | Pass | Fail at +3.3 V | Fail at +3.3 V |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 151.4 W | 301.7 W | 457.8 W | 604.8 W | 787.0 W |
| Efficiency | 90.7% | 91.4% | 90.1% | 88.5% | 86.2% |
| AC Voltage | 116.1 V | 114.5 V | 112.9 V | 111.3 V | 108.8 V |
| Power Factor | 0.982 | 0.994 | 0.998 | 0.998 | 0.999 |
| Final Result | Pass | Pass | Pass | Fail | Fail |
The bequiet! Straight Power E9 CM 680 W can really deliver its labeled wattage at high temperatures.
Efficiency was between 86.2% and 91.4% during our tests. The 80 Plus Gold certification promises 87% minimum efficiency at full load. This little difference happens because the 80 Plus tests are conducted at 23° C, and we test power supplies at a temperature of at least 45° C, and efficiency drops with temperature.
Voltage regulation was an issue, with the +3.3 V output dropping below the minimum allowed during tests four and five. See table below. The ATX12V specification states that positive voltages must be within 5% of their nominal values, and negative voltages must be within 10% of their nominal values.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12VA | ≤ 3% | ≤ 3% | ≤ 3% | ≤ 3% | ≤ 3% |
| +12VB | ≤ 3% | ≤ 3% | ≤ 3% | ≤ 3% | ≤ 3% |
| +5 V | ≤ 3% | ≤ 3% | ≤ 3% | ≤ 3% | ≤ 3% |
| +3.3 V | ≤ 3% | ≤ 3% | +3.14 V | +3.11 V | +3.12 V |
| +5VSB | ≤ 3% | ≤ 3% | ≤ 3% | +4.85 V | +4.82 V |
| -12 V | ≤ 3% | ≤ 3% | -12.45 V | -12.53 V | -12.53 V |
Let’s discuss the ripple and noise levels on the next page.