Geothermal for cooling?
I used to work in the geothermal industry where we concentrated on finding and exploiting geothermal reservoirs for heating (e.g. district heating) or for steam to drive turbines for power generation.
Real WTF to hear that they were using hot water for cooling.
Looking at the CSIRO diagrams, looks like the HPC tie in is a bit tenuous -i.e they were wanting to build an experimental geothermal plant and the supercomputer could use some other energy produced.
The geothermal fluid is contained in a closed cycle system, so they are not using the fluid directly to cool, and they pump the actual cooling fluid through a cooling tower to sink the temperature, so really not exploiting the geothermal system other than (I presume) as an energy source.
Given that this is Perth, don't know why they don't just suck cold water from the sea for a heat interchanger. Provide baseline power to the area from the geothermal plant running a turbine or stirling style heat engine, rather than dumping the heat into the atmosphere.
That or locate the supercomputer somewhere else. South coast of NZ would be my pick - lots of cheap hydro with vast amounts of cool water around Manapouri