Question Consumer PCs in data centers

[igor_kavinski]

I'm not sure but I think I've read that Google, Facebook, Valve etc. use thousands of consumer PCs in their data centers (office in the case of Valve, mainly for compilation) for their computing needs as it's cheaper and they can get higher performance due to higher clock speeds in a distributed computing setup like that, as they don't have to pay exorbitantly for the reliability/redundancy features of server hardware. So without ECC RAM, I think they may do some calculation quickly on multiple computers and validate its accuracy through consensus between the participating PCs? What other large companies are saving costs and maximizing computing performance through this approach?