Simply won't work correctly. They MUST match. Even if you somehow managed to make them work, I predict bad, and unexpected things.
The reason can be relevant to microfirmware code, being uploaded to CPU inner storage, when BIOS POST does the patching of silicon bugs. The patching routine can decide to check only 1st CPU stepping and apply same patch to 2nd cpu without check. Hipotetically. But who knows what is happening in POST really.
You'll have to go to the manufacturer's documentation (for both CPU and motherboard) to find the limitations. Such drastically different CPUs as you list are unlikely to work properly. In the past, CPUs that were identical other than the exact stepping level sometimes even weren't able to be used together. "It depends".
You need support from the bridge chips, the motherboard, and the OS. All of these would have to work in concert to work with the imbalance of the CPUs. They'd have to go through programming and intensive testing for many combinations for very little gain (over an equal CPU config).