The default behavior for processing cubes is to let the server determine how much parallelism to use. Let’s face it, the server must’ve not learned to play nice with others as a kid; as such, it doesn’t always make the best decisions. But fear not, you can help it along.
When processing a cube, click on “Change Settings…”
SSAS Cube Processing
Now change the “Maximum parallel tasks” to 1, 2, or whatever is appropriate for your environment:
SSAS Cube Processing Settings
That’s all there is to it. Happy cube processing!