I used to work at a web hosting company and one of my responsibilities was managing all the VPS backups. We had a few racks for "backup servers" which were all

I used to work at a web hosting company and one of my responsibilities was managing all the VPS backups. We had a few racks for "backup servers" which were all identical boxes. We would provision CentOS on them two or three at a time and I observed the exact same thing. Some servers were always just a little faster than others. Never figured out why.