Challenges in multicore processor design include meeting demands for performance, power, and reliability. The progression towards deep submicron process technologies entails increasing challenges of process variability resulting in timing instabilities and leakage power variation. This work introduces an analytical approach for ensuring timing reliability while meeting the appropriate performance and power demands in spite of process variation. We validate our analytical model using Turandot to simulate an 8-core PowerPC™ processor. We first examine a simplified case of our model on a platform running independent multiprogrammed workloads consisting of all 26 of the SPEC 2000 benchmarks. Our simple model accurately predicts the cutoff point with a mean error less than 0.5 W. Next, we extend our analysis to parallel programming by incorporating Amdahl's Law in our equations. We use this relation to establish limit properties of power-performance for scaling parallel applications, and validate our findings using 8 applications from the SPLASH-2 benchmark suite.