Simulated Load Testing
To provide accurate and consistent results in all of our PSU testing, Overclock3D uses professional grade DC electronic load equipment capable of placing a sustained load of 3690w across a total of six rails (including +5vsb and -12v) on the PSU! This is achieved by using a combination of SunMoon and Analogic electronic load equipment which allow us to adjust amperage loads in increments as small as 0.01A while also measuring voltage and wattage readings on-screen.
During today's tests, we will be placing the be quiet 350w SFX PSU under 25%, 50%, 75% and 100% load levels at room temperature. Unfortunately, due to the size of the PSU on test today no 50°C 'hot-box' testing could be performed.
be quiet! 350w SFX Results @ Room Temperature
| || +3.3v || +5.0v || +12v || +5vSB || -12v || AC Watts / |
| Efficiency || Intake / |
| Δ Temp |
|3.75A ||4.00A ||4.25A || 0.62A || 0.12A ||105w / |
| 83.80% ||27.2°C / |
|3.37v ||5.09v ||11.92v ||5.14v || -11.90v |
|7.50A ||8.00A ||8.50A ||1.25A || 0.25A || 205w / |
| 85.85% || 27.0°C / |
|3.35v || |
|11.94v ||5.05v || -11.93v |
|11.25A ||12.00A ||12.75A || 1.87A || 0.37A || 309w / |
| 85.11% || 26.5C / |
|3.33v ||4.98v ||11.94v ||4.96v ||-11.98v |
|15.00A ||16.00A ||17.00A ||2.50A || 0.50A ||419w / |
|83.53% || 25.6°C / |
| 19.1°C |
|3.31v ||4.92v ||11.96v ||4.88v ||-12.01v |
|15.00A ||16.00A ||1.00A ||0.00A ||0.00A ||175w / |
|78.85% ||27.2°C / |
|3.34v ||4.75v ||12.45v ||5.16v ||-12.50v |
| 1.00A || 1.00A || 29.50A || 0.00A || 0.00A ||0w / |
|00.00% || 00.0°C / |
| 0.0°C |
|0.00v ||0.00v ||0.00v ||0.00v ||-0.00v |
| 15.00A || 16.00A ||23.00A || 2.50A || 0.50A || 507w / |
|82.84% || 27.3°C / |
| 28.7°C |
|3.31v ||4.93v ||11.88v ||4.86v ||-12.06v |
Starting with the results from Test 1-4 which best represent the PSU under normal usage, we can see that the +3.3v and +5v rails on the unit are reasonably stable with a drop of 0.06v and 0.17v respectively. The real shock however comes when we take a look at the results from the +12v rail which actually INCREASED by 0.04v from idle to full load. This normally occurs when the voltage regulation on the PSU overcompensates for the load and can actually end up reducing the total power output as a result. Efficiency, on the other hand is very good for such a small unit with 85% being achieved at a load of 180 - 260w.
Although it is quite unlike me to comment on the noise of a PSU given how loud the load testing equipment is, this is undoubtedly going to be an important factor in the decision of anyone purchasing a SFX PSU. Therefore, using my ear alone as the only measuring device, I can tell you that up to 200w load the SFX Power is very quiet. However as the load increases to 260w the 80mm fan speed increases significantly to the point where I imagine you'd easily be able to hear it across the room. At 350w I could actually hear the PSU above the load testing equipment, which is never a good sign!
T5 moves into the cross-load teritory and here we can see that the be quiet isn't so happy with a heavy load on the +3.3v and +5v rails and only a small load on the +12v rail. Voltages for the +5v rail hit a rather poor 4.75v and the +12v rail shoots up to 12.45v. Additionally efficiency during this test drops to around 78%. In T6 the cross-load is reversed with a minimal load being placed on the +3.3v and +5v rails and the rest on the +12v rail. Unfortunately during this test the be quiet unit refused to power on with anything above 25A on the +12v rail and therefore failed the test. What we do need to remember at this point though is that these cross-load results are highly unlikely to be reproduced by any PC system (especially a HTPC/SFF PC) in the real world. Only if you was intending to use the unit purely to power 12v devices and nothing else would this become an issue.
T7 sees the SFX Power hit a maximum output of 420w - 70w higher than that if its rated output. Given the size of the unit this is actually pretty respectable and shows that the unit has a little extra power to give should the need arise. At this load the voltages are still very respectable and efficiency is just shy of 83%.