A downloaded NAND often lacks stubbed IOSes. Use Dolphin’s IOS Manager to install clean, patched IOS versions (like cIOS 249 and 250). High quality means no "Trucha bug" errors.
Extracted NANDs (folders full of loose files) can suffer from file attribute loss, missing bad blocks, or corrupted ECC (Error Correction Code) data. A raw dump preserves the exact state of the hardware, including the OTP (One-Time Programmable) region and the SEEPROM, which stores the console’s unique serial data. wii nand download dolphin high quality