Need suggestions for system upgrade
in The Commons
Currently i am using i7 6700k,gtx 1070, 32Gb 3200mhz ddr4, samsung evo 850 pro ssd/s.
Now with the scenes i render usually takes about from 3 to 12 hrs at 4000x4000 / UHD(for wide) and i want the max(12hrs) time to be as lese as possible mins if possible.
I dont have any issue with money, time is what I dont have because of work so if money is not an issue than what system should i build.
I also game so if having a gtx cards instead of quadro wont effect too much then i will prefer gtx cards.
I will be really grateful for the help/suggestion.
Thanks.

Comments
Unformtunately saying "I don't have any issue with money" doesn't give much of a guid - e.g. is https://www.scan.co.uk/3xs/configurator/nvidia-dgx-station-deep-learning-workstation an option? (OK, not a dedicated render box and probably not that good for games, but we need some kind of guidance on what you are willing to look at.)
Adding more cards will, as I recall, increase the load on the rest of the system (for management etc.) - but if you are rendering only on the GPU now, and it is being used, I would think you'd have less than full utilisation of the CPU
Even when money isn't an issue, it doesn't make sense to buy hardware that you will never fully utilise. So there is little point in buying RTX Titan cards with 24GB of vram if you never make scenes that will require that much memory. If you could give some examples of what you normally render, it would help to give an idea of what you would be best off buying e.g. 2 genesis 8 figures with HDRI background.
That said, in your current setup you have a 1070 with 8GB VRAM. Assuming that your scenes are actually rendering on the 1070, and not falling back to CPU due to a scene exceeding 8GB VRAM, then I would say that you would be fine with cards that have 11GB VRAM. If you take a look at the tables on the first page of this benchmarking thread:
https://www.daz3d.com/forums/discussion/341041/daz-studio-iray-rendering-hardware-benchmarking/p1
then you can see that for the price of an RTX Titan (24GB), you can buy two 2080Ti cards (11GB) and have just less than double the rendering power of a single Titan RTX. You would need to ensure that your power supply unit is up to running more than one card, and also that your motherboard will have PCIE slots far enough apart to accomodate two cards.
However, only you can decide exactly what best meets your needs, so I would recommend looking through the benchmark thread above and comparing the render scores / times with the 1070 (which is listed in the tables).
If you're doing scenes with 8 characters then you may need more than just 11GB of vram. As for multiple cards, adding a second card will roughly half the render time, but a third has much less effect. There is one piece of evidence of this given by Jack Tomalin on the first page of this thread:
https://www.daz3d.com/forums/discussion/344451/rtx-benchmark-thread-show-me-the-power/p1
As for cpu/gpu in general, the cpu is nowhere near as fast as a single gpu. The only advantage of cpu rendering is that you have a lot more memory to render the scene in.
Regarding light, you are correct that iray renders are much faster with a lot of light.