(All tested on Windows 10 x64)

Fans on the Acer either go erratic, not up to maximum, are too loud, or too passive,
 do not react well to the Windows power plan settings, or they're napping. A mess.
They will most definitely annoy the crap out of you either way.

The VN7 has two fans, a big noisy one on the left, and a high-pitched little one on the right
 that I'd like to call the jet engine.

If you're here you are most likely aware of a tool called 'NoteBook FanControl', but there
 don't seem to be decent/working profiles for the VN7-791G, so I made one.

Copy the .xml to the tool's 'Config' folder and click the '…' to select it, then click 'Apply'.

Even though you use NBFC at some point, after a while, I really don't know when, controlling
 the big fan might fail and is somehow overridden by the system, a driver, the BIOS, whatever
 is causing it.
This usually shows when the fan goes erraticly up to max speed, then stops suddenly.
There is no real workaround for this, but the little fan (the jet engine) does not seem to be
 affected by this. So, in these cases what works is to set the big fan to auto, and have the
 little fan spin at low ('fanjet.cmd') or medium speeds ('fanjetmid.cmd').
I have supplied an alternative package with a couple of batch files (.cmd) that can be run
 directly. They use the excellent RW-Everything tool to control the EC (embedded controller)
 and set both fans to different speeds, depending on the batch you use.

Some tech insight and background:

To read and write fan speeds to you need to read and write the EC, embedded controller,
 of the laptop.
Each register is one byte in size and each fan has a register for:
 – the operating mode: 0x14 (20) is manual, 0x04 (4) is automatic
 – the requested speed: 0xff (255)..0x40 (64), lowest to highest, 0xff being the lowest speed
 – the actual speed (for reading)
The register positions for the two fans are as follows:
 – 0x93 (147) big fan operating mode (set to 0x14 before you change 0x94)
 – 0x94 (148) big fan requested speed
 – 0x95 (149) big fan actual speed (for read)
 – 0x96 (150) jet engine operating mode (set to 0x14 before you change 0x97)
 – 0x97 (151) jet engine requested speed
 – 0x98 (152) jet engine actual speed (for reading)

The same is true for other notebook ECs, but the register offsets might be different.
Hope this helps.