Folding@Home don't really need fast internet connection though.
So? I don't see why that would be a
problem; that it doesn't need fast internet. If anything, it's a benefit, no?
And Prime95 is CPU/RAM stress testing.
No no; Prime95 is indeed a decentralized computing project. Just some people don't know it, calculate some primes to heat their system and shut it off again.
It is the official client of the Great Internet Mersenne Prime Search (GIMPS), a volunteer computing project dedicated to searching for Mersenne primes.
Is it possible to build a decentralized supercomputer from networked bitcoin miners?
If it's decentralized then who will get the mining reward?
Miners are already globally decentralized and whichever miner submits the next valid block receives the mining reward.
Do you really think Bitcoin mining has to be centralized to be able to determine 'who will get the mining reward'?
And why do you want to make it decentralized? i feel it's better to get a group of people to make that supercomputer and share the reward among all the people who spend money on that supercomputer.
Mining and supercomputer are 2 completely different concepts. You can't mine on a supercomputer and you can't compute on mining hardware.