drivers - Nouveau or Intel - what's my system using?

Noob question. I have Nouveau, not nvidia drivers installed on a Skylake + Geforce GTX 960M Ubuntu Gnome 16.04 system.

When I go to the "Details" app it says "Graphics: Intel® HD Graphics 530 (Skylake GT2)".

As I understood it, Nouveau is an open source driver for the Nvidia card. But it looks like the intel hardware + driver (i915_bpo) is being used instead.

It works, although I'd not say it's buttery smooth, but it's highlighted the fact that I don't really understand what's going on, and I would like to!

Here's my lshw -c display output:

*-display               
     description: 3D controller
     product: GM107M [GeForce GTX 960M]
     vendor: NVIDIA Corporation
     physical id: 0

     bus info: pci@0000:01:00.0
     version: a2
     width: 64 bits
     clock: 33MHz
     capabilities: pm msi pciexpress bus_master cap_list rom
     configuration: driver=nouveau latency=0
     resources: irq:127 memory:dc000000-dcffffff memory:b0000000-bfffffff memory:c0000000-c1ffffff ioport:e000(size=128) memory:dd000000-dd07ffff
*-display
     description: VGA compatible controller
     product: Intel Corporation

     vendor: Intel Corporation
     physical id: 2
     bus info: pci@0000:00:02.0
     version: 06
     width: 64 bits
     clock: 33MHz
     capabilities: pciexpress msi pm vga_controller bus_master cap_list rom
     configuration: driver=i915_bpo latency=0
     resources: irq:126 memory:db000000-dbffffff memory:70000000-7fffffff ioport:f000(size=64)

So is nouveau being used? Is the GeForce card doing anything? What ways are there (if any) to control which gets used - while sticking with the open source software (the nvidia drivers just crash the whole thing!).

Thanks.

Although the question being off-topic until Ubuntu 16.04 will be released in April, you are asking something that is a general topic. You are using the intel graphics, the NVIDIA card is not in use. Currently installed are intel and nouveau drivers, what you describe is normal and NOT a bug.

The reason is that you are having hybrid graphics, the integrated intel graphics and the dedicated NVIDIA GEFORCE GTX 960M graphics. You only can use the NVIDIA graphics when you install the proprietary NVIDIA drivers and nvidia-prime, which provides NVIDIA Optimus support. Then you can switch between both graphics from NVIDIA X Server Settings (PRIME Profiles) application.

Here you find the information on how to properly install the NVIDIA drivers for your adapter :

Installation of the proprietary NVIDIA drivers for NVIDIA GEFORCE 9M series graphics