Yes. If you're not electronically inclined, then you could pair a pre-made capacitive touch button board (e.g.
this Sparkfun board, but there are many others) with a simple transistor (to turn the high/low output from the sensor into a switched pair the motherboard will accept in place of a switch). That board runs from 5v power, so you could power it with the +5VSB standby power from the ATX connector so the board is powered even when the Pc is off (so it;s ready to turn it on).