Is the Gtx 1070 a full 8gb of vram?

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"games that use close to 8gb of vram" - No, not really. 8GB is enough even for 4k gaming.

A GTX 1070 should be good for 3d modeling, definitely better than your 970.
It is not a workstation-class card though, keep that in mind.
Which applications will you be using specifically?

The GTX 1080 managed to beat quite a few cards designed for this professional work, in Maya 2013 and AutoCAD 2015: http://www.tomshardware.co.uk/nvidia-geforce-gtx-1080-pascal,review-33557-9.html
(In fact it placed at the very top)

And the GTX 980 was towards the top as well, so you can imagine the 1070...

"games that use close to 8gb of vram" - No, not really. 8GB is enough even for 4k gaming.

A GTX 1070 should be good for 3d modeling, definitely better than your 970.
It is not a workstation-class card though, keep that in mind.
Which applications will you be using specifically?

The GTX 1080 managed to beat quite a few cards designed for this professional work, in Maya 2013 and AutoCAD 2015: http://www.tomshardware.co.uk/nvidia-geforce-gtx-1080-pascal,review-33557-9.html
(In fact it placed at the very top)

And the GTX 980 was towards the top as well, so you can imagine the 1070 being in between them.
In other applications though, a high-end Quadro or Firepro card is the better choice for this kind of work.
Check out their SolidWorks performance, the GTX cards simply get outperformed by all professionally orientated workstation cards.

It really depends on what applications you will be using here.
 
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