Why you can trust Tom's Hardware Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.
Load Regulation, Hold-Up Time, And Inrush Current
To learn more about our PSU tests and methodology, please check out How We Test Power Supply Units.
Primary Rails And 5VSB Load Regulation
Load Regulation testing is detailed here.
Hold-Up Time
Our hold-up time tests are described in detail here.
The hold-up time we measured hits the spot, while the power-good signal lasts for shorter than required. At least it drops before the rails go out of spec, providing accurate information to the motherboard. This is a huge deal since we've seen a number of PSUs (including some high-end ones) have problems providing accurate power-good information.
Inrush Current
For details on our inrush current testing, please click here.
The inrush current with 115V is quite high, while with 230V it's normal for 650W unit.
Load Regulation And Efficiency Measurements
The first set of tests reveals the stability of the voltage rails and the PSU's efficiency. The applied load equals (approximately) 10 to 110 percent of the maximum load the supply can handle, in increments of 10 percentage points.
We conducted two additional tests. During the first, we stressed the two minor rails (5V and 3.3V) with a high load, while the load at +12V was only 0.1 A. This test reveals whether a PSU is Haswell-ready or not. In the second test, we determined the maximum load the +12V rail could handle with minimal load on the minor rails.
| Test # | 12V | 5V | 3.3V | 5VSB | DC/AC (Watts) | Efficiency | Fan Speed | Fan Noise | Temps (In/Out) | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 3.566A | 1.984A | 2.003A | 0.980A | 64.73 | 81.46% | 840 RPM | 27.7 dB(A) | 36.49°C | 0.972 |
| 12.109V | 5.028V | 3.293V | 5.078V | 79.46 | 40.16°C | 115.1V | ||||
| 2 | 8.174A | 2.981A | 3.009A | 1.180A | 129.69 | 87.07% | 840 RPM | 27.7 dB(A) | 37.38°C | 0.988 |
| 12.094V | 5.021V | 3.287V | 5.066V | 148.95 | 41.38°C | 115.1V | ||||
| 3 | 13.145A | 3.488A | 3.530A | 1.383A | 194.85 | 88.22% | 840 RPM | 27.7 dB(A) | 38.54°C | 0.994 |
| 12.078V | 5.018V | 3.283V | 5.055V | 220.87 | 42.97°C | 115.2V | ||||
| 4 | 18.118A | 3.988A | 4.021A | 1.585A | 259.73 | 88.43% | 840 RPM | 27.7 dB(A) | 39.47°C | 0.996 |
| 12.063V | 5.014V | 3.279V | 5.042V | 293.70 | 45.20°C | 115.1V | ||||
| 5 | 22.765A | 4.986A | 5.034A | 1.785A | 324.70 | 88.16% | 840 RPM | 27.7 dB(A) | 41.90°C | 0.997 |
| 12.047V | 5.010V | 3.276V | 5.029V | 368.33 | 49.23°C | 115.1V | ||||
| 6 | 27.419A | 5.994A | 6.050A | 1.990A | 389.70 | 87.26% | 1200 RPM | 36.1 dB(A) | 42.17°C | 0.996 |
| 12.033V | 5.005V | 3.271V | 5.016V | 446.62 | 50.26°C | 115.1V | ||||
| 7 | 32.083A | 7.007A | 7.069A | 2.195A | 454.65 | 86.41% | 1430 RPM | 37.0 dB(A) | 43.12°C | 0.997 |
| 12.017V | 5.000V | 3.267V | 5.002V | 526.15 | 51.50°C | 115.1V | ||||
| 8 | 36.768A | 8.010A | 8.091A | 2.404A | 519.64 | 85.43% | 1685 RPM | 39.5 dB(A) | 43.70°C | 0.997 |
| 12.001V | 4.994V | 3.262V | 4.988V | 608.26 | 52.42°C | 115.1V | ||||
| 9 | 41.889A | 8.516A | 8.624A | 2.405A | 584.59 | 84.47% | 1950 RPM | 42.2 dB(A) | 44.31°C | 0.997 |
| 11.985V | 4.989V | 3.257V | 4.980V | 692.10 | 53.27°C | 115.1V | ||||
| 10 | 46.773A | 9.033A | 9.127A | 3.020A | 649.53 | 83.30% | 2240 RPM | 45.5 dB(A) | 45.03°C | 0.998 |
| 11.969V | 4.985V | 3.253V | 4.963V | 779.71 | 54.31°C | 115.1V | ||||
| 11 | 52.278A | 9.040A | 9.134A | 3.025A | 714.58 | 82.50% | 2240 RPM | 45.5 dB(A) | 45.22°C | 0.998 |
| 11.953V | 4.981V | 3.250V | 4.954V | 866.19 | 54.88°C | 115.1V | ||||
| CL1 | 0.100A | 16.024A | 16.004A | 0.003A | 133.50 | 81.94% | 840 RPM | 27.7 dB(A) | 41.64°C | 0.990 |
| 12.092V | 4.997V | 3.262V | 5.056V | 162.92 | 48.92°C | 115.1V | ||||
| CL2 | 53.963A | 1.002A | 1.003A | 1.001A | 659.24 | 83.98% | 2240 RPM | 45.5 dB(A) | 44.28°C | 0.998 |
| 11.970V | 5.003V | 3.273V | 5.006V | 785.00 | 53.21°C | 115.1V |
For such an affordable PSU, load regulation is pretty tight! All major rails are within 1.5%, with only 5VSB exceeding 2%. The CX650M surprises us in a good way by performing much better than we were expecting. When it comes to efficiency, the CX650M easily meets the fairly loose 80 PLUS Bronze requirements, although under higher loads efficiency takes a large hit. The synchronous design on the secondary side and the DC-DC converters that generate the minor rails surely play a large role in this.
Besides good performance, the CX650M also manages to offer quiet operation (even under high operating temperatures), so long as the applied load doesn't exceed 50% of its max-rated capacity. The only downside is that Corsair's minimum fan speed is quite high at 840 RPM. It could easily be lower than 600 RPM. In any case, output noise only exceeds 40 dB(A) with 90% and higher loads.
AMD's China-exclusive Ryzen CPUs come to the retail market — Ryzen 7 8700F listed for $420 and Ryzen 5 7500F for $296
Huawei's next-gen CPU could rival Apple's current best — Kirin CPU with Taishan V130 cores rumored to match Apple M3 performance
Intel needs $2 Billion for New Ireland fab — courting three venture capital firms for continued expansion
