Super Monkey Ball (USA) crashes when using NTSC GameCube BIOS on Wii U vWii

[HVC-001]

Environment

• Nintendont running on Wii U (vWii mode)

• Game: Super Monkey Ball (USA, Canada)

• Game verified against Redump

  • SHA-1: 2cca02879db51ca2850949c7b2349cf470607cf5

• GameCube BIOS file present on SD card:

  • File: iplusa.bin
  • SHA-1: ef9194ab4804aa0aa8540d846caf291b28331165

• SD card:

  • SanDisk Ultra 256GB SDXC A1
  • FAT32
  • 32KB clusters

Issue Description

When the NTSC GameCube BIOS (iplusa.bin) is present on the SD card, Super Monkey Ball initially appears to work correctly.

However, after playing a game and saving progress, loading times progressively become longer:

• Returning to the main menu takes increasingly more time.
• Starting a game mode may leave the screen black for several seconds before loading.
• The delays become worse after additional gameplay/saves.
• Eventually the game crashes with the GameCube error screen:

"An error has occurred. Press the POWER Button to turn off the Nintendo GameCube™."

Troubleshooting Performed

Initially I suspected a storage issue, but the problem persists across different devices:

• SD card (SanDisk Ultra 256GB SDXC A1)
• USB SD card reader
• USB hard drive

The issue occurs on all of them.

I also tested with the following Nintendont settings:

• Force Progressive: ON / OFF
• Video Mode: NTSC
• Other video-related settings disabled

Disabling Force Progressive and changing video settings does not resolve the issue.

Workaround

The problem completely disappears when the BIOS file (iplusa.bin) is removed from the SD card.

Without the BIOS file present:

• Loading times remain normal.
• No progressive slowdown is observed.
• No GameCube error screen occurs.

Reproduction Steps

1. Place the verified NTSC GameCube BIOS (iplusa.bin, SHA-1 ef9194ab4804aa0aa8540d846caf291b28331165) on the SD card.
2. Launch Nintendont on Wii U vWii.
3. Start Super Monkey Ball (USA, Canada) (SHA-1 2cca02879db51ca2850949c7b2349cf470607cf5).
4. Play a stage and save progress.
5. Return to the menu and continue playing/saving.
6. Observe progressively longer loading times.
7. Eventually the game crashes with the standard GameCube error screen.

Expected Behavior

The game should behave identically whether the official BIOS is present or not, without increasing load times or crashing after saving.

Additional Notes

The issue appears to be specifically related to using the NTSC GameCube BIOS on Wii U vWii, as removing the BIOS file entirely eliminates the problem.

[carnage702]

The bios was always just c cosmetic thing and the wiiu cant even run the pal bios due to the videomode it uses, so yeah using bios might be an issue so you always have the option in the settings to "Skip IPL" to work around that without needing to remove it, have you tried usign that setting before removing it?

[HVC-001]

I haven't tried it yet with the "Skip IPL" option, but I guess it will probably work. Since it was my understanding that the BIOS was used purely for cosmetic purposes to display the GameCube startup logo, I was surprised to find that it was actually responsible for the crashes in the game.

I had considered everything from the hardware to the video modes before thinking that the BIOS file itself could be the cause. I thought it was worth reporting because I wasn't aware that using this file could have consequences for games, to the point of causing them to crash.

[Webardo]

I can confirm that enabling the "Skip IPL" setting fixes the issue. The game stopped presenting issues.