This article provides the information on the audible squeal that can be heard on portable systems equipped with a Solid State Drive (SSD).
Some portable systems equipped with solid state drives (SSD) emit an audible squeal when the system is idle or under light use. This is normal behavior.
In order to save energy when the Central Processing Unit (CPU) is idle, the CPU can be set to enter a lower-power mode, also known as a "C-State". The intent of lower power modes is to cut power use inside the CPU. In certain situations, a high-frequency buzzing noise can be heard from the system. This buzzing noise appears with a change in processor activity, SSD load, or if Universal Serial Bus (USB) devices are attached.
The noise comes from the processor’s power circuit and can only be heard when the processor is in C3 (clock-stopped or sleep) power state. The noise is generated from the processor's power circuit, which is caused by a phenomenon referred to as the Piezoelectric Effect. When a specific voltage is applied to these solid state components, they begin to resonate producing sounds that fall within the range of human hearing (15 – 20 KHz).
This is the noise that is heard from the system, and is not indicative of a problem or failure.
If the system BIOS has a C-States option, disabling this option should help eliminate the noise.