With intel HW, 2GB of RAM runs out when using just one application on Win8 (chrome + google docs).
On my linux box I have 3GB of RAM. Also on that the memory runs out if several apps are used at the same time. Also on linux, only one user at a time seem to work well with 3GB RAM. If another is logged in, resources get exhausted very fast to a halt + reboot state.
So. RAM is mandatory. 4GB is minimum. 8GB is recommended.
On android cell phone I have found that everything below 1.5GB is useless.
If people would only use apps from the 90's, then CPU cache of Power8 chip might be enough.
