None of the parts you mention are likely to be the culprit. Try replacing the PSU. If no luck, replace the motherboard. If you buy one that can accomodate your current CPU and RAM, that's not very expensive. And if you registered Windows 10, there's a good chance that you don't have to buy a new license.
I've got a puzzle here; hopefully someone can help me out. I had the same problem in the past and bought a new power cable and replaced my videocard. For a couple of months the problem was fixed. But again my pc sometimes does and sometimes doesn't turn on. There's always power; the motherboards light is on and the usb-ports have power too. Still sometimes when I press the powerbutton nothing happens; no beep, no fans turned on; nada. When I walk around with the desktop it and try to turn it on again it works, but with the BIOS notification; I have to go into the BIOS and can go out straight away. The pc will startup as normal after although the time is always different (date and time zone stays correct, only the time itself changes). I have renewed the BIOS battery, and power cable. All my other electrical appliances in my house work fine.
-16 Gb RAM
-GeForce GTX 1070Ti
Thank in advance,
warm regards - Menno