Because people frequently confuse system names here a list of systems that are not subject of the Linux/MIPS projects because they don't use a MIPS processor:
- IBM RS6000. Frequently assumed to be a MIPS system because of the R6000 processor. The RS6000 series of workstations is based on a PowerPC processor and as such you probably want to checkout the Linux PPC site.
- VaxStation. Being based on Digital Equipment's VAX architecture the Linux/VAX project is taking care if this class of systems.
- SGI Visual Workstation. There are a few i386-based variants. Latest models are based on Intel's IA-64 architecture.
- SGI Iris 1000 / 2000 / 3000 series systems. These are very old Silicon Graphics systems from the late 80's based on the Motorola 68000 architecture. As such they're subject of the Linux/m68k project.