This paper presents two timing window methodologies used in UltraSPARC-IIIi™ microprocessor design. They have improved the accuracy of timing and noise analysis. In timing analysis, timing windows are applied to calculate effective Miller factors of coupling nets; in noise analysis, they are applied to waive false noise violations. Results show that using timing window in timing analysis, 72% of the CPU-level nets have more accurate Miller factors. Thus, it reduces the number of false timing paths. During the development of this application, a simple and practical convergence rule is defined to stop the iteration. Also, the timing window application on noise analysis has identified 42% of the CPU-level noise violations which can be waived in UltraSPARC-IIIi™ chip. This significantly improved the productivity of the design.