Unlike older versions (1.6.0 and earlier), version 1.7.0 introduced a stricter BIOS verification system. It is less tolerant of corrupted, mismatched, or "custom" patched BIOS files. You need a clean, correct dump.
For years, PCSX2 used a stable numbering system (1.4.0, 1.6.0). These were "Stable Builds," meaning they were tested rigorously to ensure nothing broke. However, technology moves fast. Waiting years between stable releases meant users were missing out on hundreds of improvements. pcsx2 1.7.0 bios download