In this paper, we focus on reliability, one of the most fundamental and important challenges, in the nanoelectronics environment. For a processor architecture based on the unreliable nanoelectronic devices, fault tolerance schemes are required so as to ensure the basic correctness of any computation. Since any fault tolerance approach demands redundancy either in the form of time or hardware, reliability needs to be considered in conjunction with the performance and hardware tradeoffs. We propose a new computational model for the nanoelectronics based processor architectures, that provides flexible fault tolerance to deal with the high and time varying faults. The model guarantees the correctness of instruction executions, while dynamically balancing hardware and performance overheads. The correctness of every instruction is confirmed by multiple execution instances through a hybrid hardware-time redundancy approach. To achieve high system performance, multiple unconfirmed computati...