Internal Power Supply Board for DOL-001 model GameCubes.
If you're GameCube console isn't powering on, it's very likely this power supply board - or more specifically, the 5A fuse that's on the board. You can test the fuse with a multimeter set to continuity mode to confirm. The fuse itself is surface mounted and can be a little tricky to get to, often making it easier to just replace the entire board.
Included are 4 mounting screws and internal power cable.
This board will work with both NTSC and NTSC-J model GameCubes.