AMD Am5x86 -P75
The Evergreen 586 is based on the AMD Am5x86 -P75 which is basically a 133MHz 486. Because Evergreen fitted it's CPU with additional logic to control overdrive-mode, cache and multipliers it's adjustable to a number of scenario's you can find in older 486 sytems.
Usually you have to configure your motherboard to run 486DX CPU's (because the Evergreen has an FPU built-in). If you use the overdrive socket, which is often found on older motherboards that have an on-board soldered CPU, you have to switch the jumper over to 'OVRDRV' mode rather than 'NORMAL'. Depending on the final clock-frequency you can switch between 3x or 4x multiplier. Depending on your FSB you can calculate what your final CPU clock-frequency will be (4x25: 100MHz, 3x40: 120MHz, 4x33: 133). Usually it'll be 4x33 which gives 133MHz (original speed of the Am5x86-P75). At last but not least there is a WT/WB switch that controls Write-Through or Write-Back cache. Write-Back is faster but more complex. If the CPU proves to be troublesome then configure WT.