1. Performance and Timing: The 71V3556SA166BQGI8 operates at a higher clock frequency (166 MHz) compared to the 100BQG8 (100 MHz) and features a shorter access time (3.5 ns vs. 5 ns). At the same system bus frequency, the 166BQGI8 delivers higher data throughput and lower read/write latency. If the system bus frequency is below 166 MHz, the device remains fully backward compatible, providing greater performance margin. 2. Operating Temperature Range: The 166BQGI8 supports an industrial temperature range of -40°C to 85°C, whereas the 100BQG8 is limited to a commercial range of 0°C to 70°C. This not only enables the use of the 166BQGI8 in harsher environments but also typically indicates higher standards in manufacturing screening and reliability design, resulting in more robust performance even in standard temperature applications. 3. Power Consumption and Signal Integrity: At the same operating frequency, the 166BQGI8 may exhibit slightly higher dynamic power due to its faster silicon process. However, in a practical replacement scenario where the system clock remains at 100 MHz, its actual power consumption could be comparable to or even better than the original part. Additionally, higher-speed devices impose stricter requirements on PCB layout and routing (e.g., signal integrity, power decoupling). Signal quality at high speed must be verified after direct replacement.