In the case of computers it turns to waste heat and whatever is radiated away is not usable energy and is essentially waste heat. Computers are basically devices for converting useful energy into waste radiation.
One small exception may be microntollers that use PWM to emit a signal through an antenna, or to drive a motor. I think in that case some of the energy becomes radio waves (which may never be absorbed entirely so they may not become heat) or motion in the motor.