Want to add one more GPU

have a question please.
How to use an extra GPU in my PC for rendering purpose? under Sketchup 2018 vray next 4.
But this GPU I would like to use whenever required high speed rendering for time saving. in rest like to use this existing card for normal use. (power consuming concern)
right now I’m using using a video card GT730 (49 watt) 2GB for 3D sketchup modeling with
i7 4970K 4.00GHz 4 core(s) 8 Logical.
Gigabite Z97X- Gaming 3
24GB of ram.

Reason. heavy GPU CARD consume big amount of wattage.

Usually, you can manage the usage of dedicated graphic cards in the control software of the manufacturer of the card (NVidia, AMD, etc.(etc. is not a manufacturer and honestly, I do not know any more))
In a laptop, the energy savings options are usually set to do exactly what you ask, in a desktop, you might wanna poke around with the settings.

In general, here are some considerations:

Modern GPU’s and CPU’s are more efficient then older one’s, thus resulting in a better kWh/pixel ratio (energy per rendered pixel)

Time spent with normal modeling will also reduce

If you wish to use a much better GPU card for rendering fast, you’ll need to insert the better card in the x16 slot. So, the old GT card will need to be moved to the x8 slot, BUT check with Nvidia that the old card and the new are compatible and can be used in the same system.

You might also see if you can switch off the integrated graphics via the BIOS. …