Efficiency, Temperature And Noise
Efficiency
Our efficiency testing procedure is detailed here.
Using the results from the previous page, we plotted a chart showing the Hydro G 650's efficiency at low loads, and loads from 10 to 110 percent of the PSU's maximum-rated capacity.
As the above graph shows, the efficiency difference between 230V and 115V is notable, especially under higher loads. Of course, this applies to most PSUs since the amperage with 230V is lower, reducing energy losses. But we're used to seeing a delta of around 1.5 percent. In this case, it exceeds 2 percent. With 230V, the HG650 is among the most efficient Gold-rated 650W PSUs we've tested.
Efficiency At Low Loads
In the following tests, we measure the efficiency of FSP's Hydro G 650 at loads significantly lower than 10 percent of its maximum capacity (the lowest load the 80 PLUS standard measures). The loads we dialed were 20, 40, 60 and 80W. This is important for representing when a PC is idle, with power-saving features turned on.
| Test # | 12V | 5V | 3.3V | 5VSB | DC/AC (Watts) | Efficiency | Fan Speed (RPM) | Fan Noise | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.190A | 0.480A | 0.468A | 0.190A | 19.60 | 68.10% | 0 | 0 dB(A) | 0.902 |
| 12.223V | 5.168V | 3.405V | 5.152V | 28.78 | 115.0V | ||||
| 2 | 2.430A | 0.957A | 0.970A | 0.385A | 39.70 | 78.96% | 0 | 0 dB(A) | 0.944 |
| 12.132V | 5.167V | 3.400V | 5.143V | 50.28 | 115.0V | ||||
| 3 | 3.669A | 1.455A | 1.470A | 5.133A | 59.89 | 83.76% | 0 | 0 dB(A) | 0.961 |
| 12.102V | 5.165V | 3.395V | 5.133V | 71.50 | 115.0V | ||||
| 4 | 4.888A | 1.931A | 1.945A | 0.780A | 79.73 | 86.43% | 0 | 0 dB(A) | 0.971 |
| 12.107V | 5.163V | 3.390V | 5.118V | 92.25 | 115.1V |
Efficiency is satisfactory under light loads. However, we would like to see greater than 70 percent efficiency in the 20W test.
It's worth mentioning that the PSU operates passively in these tests, even though the temperature inside of our hotbox is above 34 °C.
5VSB Efficiency
The ATX specification states that 5VSB standby supply efficiency should be as high as possible, recommending at least 50 percent with 100mA of load, 60 percent or higher with 250mA of load and 70 percent or higher with 1A or more of load.
We take four measurements: one each at 100, 250 and 1000mA, and one with the full load the 5VSB rail can handle.Â
| Test # | 5VSB | DC/AC (Watts) | Efficiency | PF/AC Volts |
|---|---|---|---|---|
| 1 | 0.102A | 0.53 | 80.30% | 0.102 |
| 5.160V | 0.66 | 115.1V | ||
| 2 | 0.252A | 1.30 | 82.80% | 0.211 |
| 5.155V | 1.57 | 115.1V | ||
| 3 | 1.002A | 5.14 | 84.40% | 0.383 |
| 5.126V | 6.09 | 115.1V | ||
| 4 | 3.502A | 17.65 | 80.85% | 0.487 |
| 5.041V | 21.83 | 115.0V |
This is hands-down the most efficient 5VSB rail we have ever seen in a PSU, regardless of its efficiency rating. We're usually satisfied if efficiency goes above 80 percent in one test. However, the Hydro G 650 manages to score above 80 percent efficiency in all four of the tests. That's what we call amazing 5VSB performance!
Power Consumption In Idle And Standby
| Mode | 12V | 5V | 3.3V | 5VSB | Watts | PF/AC Volts |
|---|---|---|---|---|---|---|
| Idle | 12.244V | 5.173V | 3.412V | 5.161V | 8.15 | 0.613 |
| 115.1V | ||||||
| Standby | 0.05 | 0.007 | ||||
| 115.1V | ||||||
In the table above, you'll find the power consumption and voltage values of all rails (except -12V) when the PSU is idle (powered on, but without any load on its rails), and the power consumption when the PSU is in standby mode (without any load, at 5VSB).
At only 0.05W, phantom power is very low, which helps explain the 5VSB rail's high efficiency (particularly under light loads).
Fan RPM, Delta Temperature And Output Noise
Our mixed noise testing is described in detail here.
The first chart below illustrates the cooling fan's speed (in RPM), and the delta between input and output temperature. The results were obtained at 34 °C (93.2 °F) to 47 °C (116.6 °F) ambient temperature.  Â
The next chart shows the cooling fan's speed (again in RPM) and output noise. We measured acoustics from one meter away, inside a small, custom-made anechoic chamber with internals completely covered in sound-proofing material (be quiet! Noise Absorber kit). Background noise inside the chamber was below 18 dB(A) during testing, and the results were obtained with the PSU operating at 34 °C (93.2 °F) to 47 °C (116.6 °F) ambient temperature.Â
The following graph illustrates the fan's output noise over the entire operating range of the PSU. The same conditions of the above graph apply to our measurements, though the ambient temperature was between 28 °C (82.4 °F) and 30 °C (86 °F). Â
Up to around 130W, the Hydro G 650 operates in passive mode. And through most of its operating range, the PSU's noise is between 31-34 dB(A). Under loads exceeding 410W, the fan speeds up, and with more than 470-480W loads the noise reaches 37-40 dB(A). You can't call this a noisy PSU per se. However, there are competing products in this category that are quieter.