CPU, memory and disk space are all finite resources for the device.
Gauges work well for this because the total usage of the resource can be shown in this context. At at glance, you can see how much of the resource is consumed, how much of the resource remains and also how much of the resource there is.
Note that gauges don't have to be represented as semi-circles or circles they can also be done using a bar e.g. a scale on an analog thermometer.
Either a pie chart or a component/stacked bar can be used to show a breakdown of resource usage.
However, both breakdown as visual representations when there are too many divisions being illustrated. You can always fall back on a regular bar chart if this is the case.
You will need to ask your users what they would expect to see on the dashboard.