The actual CPUs are pretty impressive, and operate at 3-4.5GHz range. The system will have up to ~80 of these, so it would effectively blow away a Mac Pro. Let'

The actual CPUs are pretty impressive, and operate at 3-4.5GHz range. The system will have up to ~80 of these, so it would effectively blow away a Mac Pro. Let's be honest though, at the prices IBM fetches for these (millions for the top end), you could build a VERY healthy Hadoop cluster. The reason why these are kept around is that the custom software that runs on them often implements very complex business rules that are otherwise undocumented (the code is the documentation). If you're talking about a financial institution, the mainframe IS the business. As far as reliability, these things are rock-solid and proven, but mainstream distributed systems design has pretty recently surpassed the mainframe model IMHO. It's relatively simple (compared to just a few years ago) to implement clustered data processing using MapReduce, replicate the data across multiple datacenters, and not care about individual node failure.