For as long as I’ve been involved in computing, and especially HPC, powers of two have reigned supreme. Often for no good reason – for many compute jobs running on 128 processors is no more or less ‘right’ than running on 130 processors. Of course, sometimes system architecture (e.g. nodes sizes, network topology) or service policies (e.g. queue limits, ‘capability’ focus) makes a certain processor count more favourable, as do characteristsics of applications (e.g. scaling limits, nature of the domain decomposition). Systems are usually specified with 1,2 or 4GB of memory per CPU. But even when powers of two aren’t used, we usually still stick to even numbers (why?).Now AMD is to take even this away from us with the launch of a 3-core processor (The Register). And with the previous revealing of the 3-socket server (The Inquirer) – the prospect of 9 core servers becomes real.It would be intersting to compare the performance of an 8 core job across the variants – a 2 socket quad core system, a 4 socket dual core system and a 3 socket tri core system.