Power draw correlation with VX450 electrical noise

I have recently installed a new VX450 and noticed the 'cricket chirp', also called 'coil whine', coming from the PSU at certain levels of load power. Many users describe similar noise occurring during mouse movement, page scrolling, or while playing a 3d game. However, the only consistent correlation I have found within my own system has been with power draw.

 

All numbers below are AC input power and should not be taken out of context (only compare with other numbers presented here).

 

Input power is measured by a Kill-A-Watt unit. CPU loading is accomplished with Intel's Thermal Analysis Tool. The CPU was run at a variety of settings ranging from 1.2GHz @1.2V to 3.0GHz @1.4V. GPU power state is monitored with GPU-Z. The GPU idles at 157MHz @.95V but ramps to 700MHz @1.1V during load (including 2d tasks such as window resizing).

 

80-95W

In this power range there is no noise unless an action is taken that increases power draw of either the CPU or GPU, such as page scrolling, window resizing, or other UI refreshes

 

105-125W

Here there is constant electrical noise, regardless of software state or combination of hardware activity

 

135-180W+

No electrical noise, again regardless of the scenario

 

There is no specific action, such as CPU usage or video card activity, that will trigger the whine. Some examples:

 

I can adjust from constant noise to none while in the BIOS by overclocking the CPU, pushing power draw up above 130W. I can adjust from no noise at idle at the windows desktop to constant noise by swapping in a video card that pulls an extra 25W idle power. I can put a workload on 1 CPU core to cause the whine to start and simultaneously load a second core to cause it to stop with each core pulling about 25W.

 

My purpose here is not to condemn the VX450 but to offer insight into further troubleshooting methods for fellow users. The motherboard was kept constant throughout testing and could very well be the cause of conflict. An RMA through Corsair can be arranged if desirable, though working through the vendor would likely be more convenient for me. A downgrade to a 300W range power supply may be in order to keep the PSU above ~20% DC load at idle and preempt any further issues.

I've replaced the VX450 with an identical unit through my vendor and am pleased to report that the electrical noise is completely gone.