Interior view of an ATX SMPS: below A: input EMI filtering and bridge rectifier; B: input filter capacitors; "Between" B and C: primary side heat sink; C: transformer; Between C and D: secondary side heat sink; D: output filter coil; E: output filter capacitors. The coil and large yellow capacitor below E are additional input filtering components that are mounted directly on the power input connector and are not part of the main circuit board.