Multicore architectures are becoming increasingly prone to transient faults and data corruption. Relying on a multicore architecture is the common solution for increasing performance and scalability of core applications including transactional applications. In this paper we present SoftX, a low-invasive protocol for supporting execution of transactional applications relying on speculative processing and dedicated committer threads. Upon starting a transaction, SoftX forks a number of threads running the same transaction independently. The commit phase is handled by dedicated threads for optimizing synchronization's overhead. We conduct an evaluation study showing the performance obtained with the implementation of SoftX on a 48 cores AMD machine, running List, Bank and TPC-C benchmarks. Results reveal better performance than classical replication-based fault-tolerant systems and limited overhead with respect to non fault-tolerant protocols. We ported SoftX to a message-passing architecture, Tilera TILE-Gx. Hardware message-passing is an important emerging trend in multicore architectures. Our experiments on Tilera show that SoftX is still more efficient than replication.