This article gives you a detailed guide for the construction of a Diskless HPC Cluster using Fedora as Operative System. The final purpose of the Cluster is to run both RAMS (Regional Atmospheric Modelling System) and CAMx (Comprehensive Air quality Model with extensions) Numerical Models in a Parallel and/or Grid manner. Themes ranging from CPU Architecture Selection, passing by Operative System Configuration to Cluster Final Tuning are treated in this article. The information presented here, may be used to construct both a Diskless HPC or a Beowulf Cluster with Parallel and/or Grid computing capabilities, intended to run Numerical Models or any other MPI capable application using an UNIX distribution.