A customSonnet Crescendo G3 L2 upgrade for the Twentieth Anniversary Macintosh, modified byherdwith a Motorola 7400 G4 CPU and 512K backside cache. This custom Sonnet upgrade card was featured on the 68kMLA forums in 2022 and inspired Action Retro to subsequently create a similar custom TAM upgrade for YouTube. These are the only two examples that I know to exist.
This upgrade card runs at a native 300MHz and using Sonnet Clocker enables it to run at 300, 350, or 400MHz in a Twentieth Anniversary Macintosh.
For the discriminating buyer who needs to have the absolute best Twentieth Anniversary Macintosh in existence... now's your chance.AI wants to say the following: The Sonnet Crescendo L2 G4 300 400 MHz CPU Upgrade is a vintage part designed specifically for the Twentieth Anniversary Mac (TAM). Made by Sonnet in the United States, this CPU upgrade unit is compatible with Apple products and offers a significant performance boost for vintage computing enthusiasts. With a vintage appeal and a focus on enhancing the capabilities of older Mac systems, this CPU upgrade is a unique and specialized addition to any collection of vintage computing parts.