Most supercomputers are built for performing general computing tasks that require huge resources because of their inherent complexity. The processors must be able to perform a extremely wide range of operations. But in bitcoin this is completely not the case... we need high speed hashing of SHA-256 algorithm... ie. the same few operations over and over as fast as possible and running in parallel as many times as the hardware allows for. The hardware in each case are almost like polar opposites.
I have to disagree with this. Most supercomputers are built for massively parallel operations, and the really quick ones use -- you guessed it, graphics cards from common vendors like nVidia to achieve this.
Simulating a nuclear detonation or parts of the human thought process is of course more complex than SHA-256, but that does not preclude such systems from having a lot of hashing power either.
The
Cray Titan uses AMD Opteron cpu's combined with nVidia Tesla GPU cards. It has 18688 of each, and it is rated at a theoretical peak of 27 peta flops. How many flops for 1 hash? I don't honestly know. If it is 1000, then it could hash at 10^6 Mhash/s, which is pretty good (1000 THash/s) - plenty for a 51% attach if my finger math is correct.
Anyway, I'm not talking about the supercomputers we know about. I'm talking about stuff that is hidden away, things we don't know about. One reason the US government isn't doing very much to stop Bitcoin might be because it knows that it can stop it anytime it wants to, by the flick of a switch.
-Michael