Thanks for your replies:) Ok so I decided to buy new CPU and do you think that Ryzen 1700 (with OC) will be a good choice? It's looks that after OC it's as fast Ryzen 1800X.
And one more question. At the beginning I was using RT just for preview and for the final render I wanted to switch to Adv but the image was muuuch brighter or much darker on Adv than on RT (I don't remember but I think it was brighter) and that's why now I use only RT. But can you tell me why there was so big difference? I didn't change camera exposure settings etc. I didn't change anything, just pressed render on RT and image was fine, then switched to Adv and image was soo bright and after that I switch to RT again and image was fine again. But I'm sure it wasn't color mapping mode that made the difference.