DOGEY

I am gonna say Intel. If you are aiming 120/144Hz. Also, because, the 9700K runs hotter than your 2500K you will need to buy a better cooler.

It will work. Everything under 1066Mhz should work.

If you are going to OC the cooler you choose is good. If you don't OC the stock cooler is enough.

The third one.

The 2nd one. I see that the second pc is better. RX480 vs Vega 11. Pfff. It's obvious the RX480. And the i5-7400 is good.

Change the CPU to 2600. It's better here's proof: https://cpu.userbenchmark.com/Compare/AMD-Ryzen-5-2600-vs-AMD-Ryzen-5-1600/3955vs3919. Then change the ram to 3000Mhz and a B450 motherboard (Asrock is a good choice if you are not going to OC).

4 Gigabyte motherboards died on me. MSI B450 Mortar has better VRAM and at least has VRAM. I think you choose the best motherboard here. You can try getting 2666 ram and then OC to 3000 (It will be easier but really ram OCing is painful)

Yes, it will be really affected. At least 3000Mhz ram. If you think that 57 degrees are too much get a better cooler. ASRock B450M Pro 4 ITX will be a good choice if you are not going to overclock. And as an owner of an Asrock motherboard, I recommend them. And is 80$. Also, you can just say what's your budget.

The onboard graphics are -63%. https://gpu.userbenchmark.com/Compare/Nvidia-GTX-750-Ti-vs-AMD-RX-Vega-8-Ryzen-iGPU/2187vsm441833

The upgrade on the card is good. But for 78$ and 8% difference on the CPU doesn't seem much. Better have some money left and with a good card.

Did the guys on the videos OC their CPU? That can make a difference between your and their's 8600K's. Also, try default settings and then compare the temps to OC.

I didn't want to be sarcastic. Even I searched for Asus motherboards. Don't get me wrong Asus motherboards are good. Just sometimes the price can be high or the motherboard will not be the best.

Ok...We are going with Asus no problem.