Chill Innovation CP-350A PSU

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For a complete rundown of testing equipment and procedures, please refer to the article SPCR's Revised PSU Testing System. It is a close simulation of a moderate airflow mid-tower PC. Here's a quick summary:

Measure temperature of ambient air, case, and PSU exhaust
Digital readout thermometer. There are several in the lab that are used. (Like DigiDoc.) They measure within ~1°C of each other, which is good enough for our purposes. Powered by the PSU being tested. (1~2W power draw.)
Measure voltages across fans and DC output line
Heath / Zenith SM-2320 and Circuit-Test DMR2208 multimeters. These are ordinary multimeters that have been compared against a much more expensive lab instrument and comes very close (within 2%) on readings of 0~20VDC. Plenty good enough for our purposes.
Load PSU to specific DC output power loads for each voltage line

DBS-2100 PSU Load Tester. Made specifically for testing computer power supplies, it consists of a large bank of high power precision resistors along with an extensive selection of switches on the front panel calibrated in Amps (current) and grouped into 6 voltage lines: +5, +12, -12V, +3.3, -5, +5SR. Leads from the PSU plug into the front panel, and there are taps for taking voltage readings for the 3.3V, 5V and 12V lines. It is capable of loading a PSU to over 600W DC power output.

Measure AC power, power factor (PF), VA, AC line voltage
Kill-A-Watt Power Meter. An inexpensive consumer power meter with very good accuracy and a host of useful functions.
Measure noise in dBA from 1 meter distance B&K model 2204 sound level meter. This professional caliber SLM dates back to 1978, weighs over 10 pounds, and is completely analog in design. It has a dynamic range that spans over 140 dB. The unit's absolute sensitivity reaches below 0 dBA. A quiet environment is a prerequisite to low noise testing; the lab has been measured down to 16~17 dBA at night. A 12 dBA adjacent room is also available for PSUs that are quieter.
Thermal environment directly related to the power delivered. Custom Thermal Simulation Box. A NEW ADDITION to the lab, it ensures that the heat generated by the PSU during testing actually creates the thermal ambient of its working environment. So the temperature seen by the PSU is directly tied to how much power it generates. This is probably the most thermally realistic testing rig for PC power supplies used by any testing lab. Please see SPCR's Revised PSU Testing System for full details!

Normally the fan voltage is tapped to monitor the voltage, but neither the black nor the red lead provided any reasonable voltage values that made any sense. Some time was spent trying to resolve this issue, but in the end, I opted to forgo the voltage monitoring. The sound pressure level measured is more important anyway.

The testing was conducted in the "sound lab", a 20' x 10' x 8'(ceiling) carpeted den with heavy drapes on windows across one of the short walls. Acoustics are fairly well damped. Ambient conditions during testing were 20°C and 15 dBA, with input of 120VAC at 60 Hz.

Chill Innovation CP-350A
DC Output (W)
AC Input (W)
Case Temp (°C)
PSU Exhaust (°C)
Fan Voltage
Noise (dBA/1m)
NOTE: The ambient temperature during testing was a couple degrees lower than in recent PSU reviews. Please take this into account when comparing test data.


A NOTE on Voltage Regulation

VR is an easy test for any good PSU to pass as long as it is operating within its power output limits. Many will be within 1% accurate. The variances commonly found in reports from motherboard voltage sensors (such as provided by Motherboard Monitor) are not at all useful to test power supplies. The problem is that those readings are the sum of interactions between the motherboard, its power circuitry, the connectors and cables between the board and the PSU, and the PSU itself.

The output voltage of the PSU must be monitored in isolation from external influences while it is doing work (delivering current). The only practical way to do this is to use a voltmeter (multimeter) to check the voltage across the terminals to which the power is being delivered.

In SPCR's VR testing, a multimeter is connected to each of the voltage lines for several minutes. The voltage reading is monitored continuously while the loads on each and all the lines is varied, and the peaks and valleys recorded manually.

1. VOLTAGE REGULATION is within the required -/+5% on all lines in any nominal combination of loads. There is a bit more variance than average for SPCR PSU tests; it's not as good as some of the other PSUs tested. The low and high voltage seen on each of the main lines is shown:

  • +12V: 11.6 to 12.5
  • +5V: 4.7 to 5.3
  • +3.3V: 3.2 to 3.45

2. AC : DC Conversion EFFICIENCY is below average for recent PSUs tested. Keep in mind that most PSUs tested by SPCR are high quality upmarket units.

3. POWER OUTPUT: The unit ran with good stability at all output levels. At the full aggregate 330W output on the 3.3V + 5V + 12V lines, it is close to overload. A mere 10W more on the 12V line was enough to trigger a shutdown, from which it recovered without incident when powered back up at a lower load. Whether this shutdown was provoked by overheating or overcurrent is not possible to tell.

4. POWER FACTOR is excellent as expected for an Active PFC unit, staying at around 0.98-0.99 throughout the testing.

5. FAN VOLTAGE: As mentioned before, I was unable to monitor this voltage.

6. NOISE was measured at 1 meter from the exhaust grill, with both the SLM and the PSU at least 1 meter from walls. All other noise sources (including the fans in the test setup) were turned off during measurements and listening.

Subjectively, the Chill Innovation CP-350A is very quiet at startup and at low power. But by the time the 150W output mark is reached, it is loud enough to become the primary noise source in a very quiet PC. The noise continues rising and hits a maximum of 35 dBA at around the 300W mark. This is a modest volume compared to most PSUs at full power output.

The fan has a bit of electronic noise at low speed, but the overall level is low enough that this should not be an issue. This noise gets obscured beneath the usual whoosh of wind turbulence as the fan speeds up. There was no high frequency component from the fans or the electronics in this sample. (Coil noise is often the result of interactions between components, however, so the absence of this noise in the lab does not ensure its absence when the PSU is connected to PC components.)

A CAUTION: The noise-to-power performance achieved here is specific to prevailing test temperatures. In other words, if your ambient temperature is 35°C and your case temperature measures 45°C, you can expect higher noise, regardless of the electrical load.


The Chill Innovation CP-350A provides acceptable performance despite appearances that suggest low cost manufacturing. It is very quiet at lower power levels, moderately quiet beyond, and surprisingly muted at full power. Do note that the testing environment ambient temperature was 2°C cooler than in the last couple of recent PSU tests. This can have an effect on PSU temps and noise.

While it is unlikely that any desktop systems could really draw 350W total in a real application, the current capability of the 12V line may not be high enough to handle a PC with a very high power CPU + VGA card that requires additional 12V power, especially with a lot of peripherals.

The short cables could pose a problem in larger or more component-loaded systems. Its efficiency is reminiscent of an earlier generation of PSUs.

It's hard to muster up much enthusiasm for this product, given the availability of other quiet PSU options that inspire more confidence. If the street price is lower than models from Nexus, Seasonic, Zalman, Fortron, Enermax Noisetaker and others, then it's probably a fine choice for more modest systems.

Our thanks to Chill Innovation for the opportunity to examine the CP-350A.

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