Note: This is more of a discussion piece, not asking/suggesting to to this the current OS/firmware/software.
I'm wondering how possibly this would be, particularly with Linux and low-level (kernel level, maybe?) nodes/code to make it possible. Basically I mean taking a CPU you would use now for gaming and add another processor with a bunch of cores that run at a lower frequency.
This could take one of 2 methods:
Multi-CPU motherboard. With high clock/IPC single/dual/quad core CPU and one (or more) with a high core/thread count (20+).
An actual separate swarm machine made up of a cluster of Raspberry Pis or similar microcomputers, hooked up through ethernet. I think the issue here would be actually integrating it into the system where it would see the cluster as additional CPU cores/threads and integrating it where they can be intelligently scheduled work, and have it sent to them directly like a real piece of hardware rather than needing the same OS and program setup.
In either case... with something like rendering using Handbrake, the 'swarm' threads would get their own frames (likely from the end of the workload). Near the end of the job If the faster threads do them significantly faster (they likely would) then the frames would be given to them instead of the swarm threads.
Things like games would likely use the 'main' CPU unless it could saturate all of the other threads (and what was left is small and not too needed instantly) whereas the swarm could be used for anything highly parallelized (and again, in some cases BOTH could be used).
Just some thoughts for both high thread+high frequency/instruction (my other thought being a CPU having 2^n cores with lowering frequency: [email protected], [email protected], [email protected], [email protected]) in one system without drawbacks of traditional clusters (like needing recompilation of software to gain any benefit).
Of course it wouldn't be used to full capacity in most scenarios, but even simply best of either world would be good. It'd all be up to how well applications support multithreading and how intelligent CPU scheduling could be (taking care to give jobs to the threads that are most suited to complete them).