An Applied Investigation Into Graphics Card Coil Whine

jones_supa writes We all are aware of various chirping and whining sounds that electronics can produce. Modern graphics cards often suffer from these kind of problems in form of coil whine. But how widespread is it really? Hardware Canucks put 50 new graphics cards side-by-side to compare them solely from the perspective of subjective acoustic disturbance. NVIDIA's reference platforms tended to be quite well behaved, just like their board partners' custom designs. The same can't be said about AMD since their reference R9 290X and R9 290 should be avoided if you're at all concerned about squealing or any other odd noise a GPU can make. However the custom Radeon-branded SKUs should usually be a safe choice. While the amount and intensity of coil whine largely seems to boil down to luck of the draw, at least most board partners are quite friendly regarding their return policies concerning it.

Comments

The Cause

[labnet]

I've designed lots of these little switch mode supplies. (SMPSs)
The noise comes from the inductors. Inductors are coils of wire around a ferrite. When the current changes through the wire, the wire physically expands and contacts from every other wire. This is the source of the noise. (SMPSs normally switch from 200kHz to 2MHz, so well outside our audio range)
There are a few things a designer can do.
1. Encapsulate the coil. This holds the wire tighter together and can minimise noise, but is only usually used in large inductors like those in invertors for UPSs or solar.
2. Eliminate subsonic oscillation with good multi-pole compensation. Switch mode power supplies have, have first second and third order responses which require filters to damp them. If you don't design these filters well, you can get subsonic oscillation which falls into the audio band. The power supply still regulates OK, but you can get that annoying whine.
3. Occasionally the noise can also come from a periodic load with that falls into an audio range. More capacitors on the output can help that.

Also, very very occasionally, it can come from ceramic capacitors that use a high k dielectric that are microphonic, but in my experience it is usually the capacitor acting as a microphone that upsets the circuit.