quote
”果然嗡嗡聲不見了, 只剩下硬碟讀寫時,清脆的響聲”

NOISE: x 3
1 motor: 7200 rpm high pitch 120 hz
2 seek: “只剩下硬碟讀寫時 ,清脆的響聲”
3 case共振
1 and 2 still need thick case and insulation.

http://www.silentpcreview.com/section13.html?from=30