New answers tagged hardware
Using 2 screens for GIS is already out of fashion. For worldwide datasets, just use a spherical screen.
To answer your refined question, YES, you can indeed undock the Catalog, TOC, Toolbox, etc windows and put them on the secondary monitor:
Two screens are better than one for everything except moving house.
Yes you can. With both ArcGIS and QGIS.
For image processing, there are currently two projects that deal with this: Geotrellis GIS Tools for Hadoop Those projects are dealing directly with parallel systems (as GPU processing and High Performance Computing), but not limited to it , and being able to implement on distributed systems. GIS Tools for Hadoop was initially designed to work on a ...
I wouldn't overgeneralize and say "GIS software doesn't use GPU for processing" when talking just about ArcMap. Anything that uses OpenGL or DirectX with shaders will take advantage of GPU memory: Google Earth, ArcScene/ArcGlobe, ENVI, OpenSceneGraph, AmigoCloud, CesiumJS, etc.
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