1. Performance and Timing Specifications: The 166BQGI8 operates at a higher clock frequency (166 MHz) compared to the 133BQGI8 (133 MHz) and offers shorter access time (3.5 ns vs. 4.2 ns). While the 166BQGI8 provides higher data throughput and faster system response, it imposes stricter timing margin requirements. When substituting, ensure that the interface timing of the controller (e.g., CPU/FPGA) still meets setup and hold time specifications at the higher frequency. 2. Power Consumption and Signal Integrity: Within the same voltage range, higher operating frequency typically leads to increased dynamic power dissipation and greater sensitivity to power supply noise. After replacement, system power integrity (PI) and signal integrity (SI) must be evaluated, particularly the quality of bus signals at the elevated frequency. This may require enhanced termination or optimized PCB routing. 3. Controller Compatibility: Although the interface protocol (ZBT SRAM) remains identical, the controller must be configurable to support operation at 166 MHz. If the original system was designed for 133 MHz, direct substitution may result in unstable operation at the higher frequency due to controller configuration limitations or insufficient clock tree capability.