Thank for the replies guys.

@filibis said:

Simply check those GPUs you found in benchmarks results:
https://www.videocardbenchmark.net/high_end_gpus.html
https://benchmark.chaosgroup.com

I've found that Passmark charts are like "generalised" and I dont trust them 100% in a case of SketchUP.

Chaosgrous benchmark also are tough nut while they're tested on x20 core platforms and compared with 4x 1080ti setups.

The most important thing that troubles me is CUDA cores and their performance on workflow.

I can't afford 1080 ti

It's:
GTX 1070Ti: (12338 G3d Mark) 2430 CUDA Cores - 2 000 PLN (NEW)
VS
GTX 980Ti: (11314 G3d Mark) 2816 CUDA Cores - 1 500 PLN (Aftermarket)
VS
Titan Z: (7718 G3d Mark) Old piece but still has 5760 CUDA Cores! - 1600 PLN (Aftermarket)

If CUDA Cores measure V-Ray render performance I'm blindly going with old GPU.

@paul russam said:

I’m in the process of doing something similar and found this site https://pcpartpicker.com
Great base, thanks, it comes handy!

Hello everyone!

This is my first post in a forum, while I'm actually following and learning from it for a long time.

I'm architecture student and I find Sketchup a great tool.

Time has come to build new workstation, because I'm getting tired of my mobile Dell M6600 performance.
I need something stationary and as much powerfull for the value as I can possibly get.

I've done a lot of reaserch, and more time I'm spending on that task, more confused I get.

I built last PC few (like 5) years back, and got some things to catch up.

I'll focus on most important stuff: CPU+GPU (rest I can handle myself)

CPU:
clock speed>core number
core number - 2nd important but sill, it'll my only rendering workstation

I decided to go for i7 over Xeon due to its better clock speed/price rate.
Still wondering on i7 generation, I consider 2nd hand parts. Rather than upgrade in the future, I'll change whole rig after 2-3 years, so maybe older 4970k would be a choice, or newer 6700K/6800K?

GPU:
Here is far more fishy.
GPU is responsible for viewport smoothness and RT renderin (witch i find great for learning V-Ray)

I found CUDA cores are responsible for RT rendering preformance so Iconsider few options:

1050ti - cheapest/newest budget version
980ti - aftermarket expensive oprion
Titan Z - oldest but has about 5k CUDA cores (so it should get me boost for RT and enough viewport smoothness)

Can you help me with a bit of practical feedback?
How does CUDA cores really affects render speed and is going for GPU all the way for that is worth it?

Any help appreciated.