Why are you worried about idle temps? They are irrelevant, unless you have higher than recommended maximum temps?
If your idle temps were 79°C, it wouldn't matter, so long as your steady state, 100% full load maximum temps were not higher than 80°C. And, while that IS an exaggeration, because something would have to be tremendously wrong for you to actually have a 79°C idle temp, and you'd never manage to stay within recommended maximum temps, if you could, it would be fine. There is no benefit to having a 30°C idle temperature over having a 40°C idle temperature so long as you are thermally compliant at the other end of the spectrum and are not exceeding 80°C while running Prime95 Small FFT with AVX/AVX2 disabled, or OCCT small data set, also with those AVX instruction sets disabled, for 15 minutes.
If you're using the stock cooler, THAT is the problem you should be focusing on, not what the idle temperature is doing, unless of course the maximum temps are out of recommended range in which case THEN idle temps matter because they become an indicator of the problem.
What CPU cooler are you using?
What case?
How many case fans, where exactly are they located and exactly what direction is each case fan oriented to blow?