Re: Super computer?
If they have semi-decent performance-wise you could use them as individual servers and rent them out. You don't even have to put a great deal on the servers application-wise, as long as the infrastructure is set up and the OS is set up with remote access, somebody would happily rent the space.
Athlon II x4 645 || 1TB 7200rpm HDD || EVGA GTX 650Ti OC || 8GB DDR3 RAM || Windows 7 Home x64
i5 4210M || 500GB Samsung EVO 850 SSD || GeForce 825M || 16GB DDR3 RAM || Windows 10 x64