Signal reliability of nano-scale interconnects is a major cause of concern at subthreshold voltages. This paper deals with the subthreshold operation of carbon nanotube (CNT) bundle interconnects of two different geometries viz. square CNT bundles (S-CNT) and triangular CNT (T-CNT) bundles. The output waveforms of the two interconnect geometries are studied to find out the effects of ON/OFF times and swing on the rising/falling propagation delays and power dissipated by the interconnects. Six cases of driver/load configurations comprising of inverter and transmission gates are considered in this study. Results show that the performance of CNT bundle interconnects is dependent on the timing and swing of the output waveforms. Also, triangular CNT bundle interconnects showed better performance in terms of propagation delay and power dissipated compared to traditionally proposed square CNT bundles. © 2021 Informa UK Limited, trading as Taylor & Francis Group.