CharlyGMP

I have two 3600's (not X or XT, purchased Nov 2019 and March 2020) in my house. Both OC to 4.2ghz all core at 1.25V just fine. They run cooler and faster, single and all core loads, than with PBO.
 
To verify what is voltage seems "safe" I set PBO and monitored voltages under various loads. Blender is a heavier all core load than cinebench, and I found voltages right around 1.35V with PBO. So, in my mind 1.25V is very safe
 
My gaming OC is 4.4ghz at 1.35V. It might degrade my chip over time, but I doubt it will anytime soon. Especially when PBO runs hotter in games than this OC.
 
Three main things cause chips to degrade; temperature swings, voltage and amperage. Keep these in check and your chip will be fine.
 
*Edit* also be careful with LLC. Have some voltage drop is good. Too high of an LLC can cause the VRMs to overshoot when load goes away and slam your chip with higher voltage for a few milliseconds. I use medium too, but wouldn't want to go higher.

This is not a most people thing, and make sure you're not looking at what people are doing with 3600X. The 3600X boosts to 4.4Ghz, so it has more headroom for overclocking. Getting a 4.2Ghz all-core OC on that would be reasonable. Then, given that the 3600X is basically just a binned 3600, it's theoretically possible that you might win the silicone lottery and get a 3600 that can OC to 4.2Ghz, but that would not be the norm.

Exactly what I tought, thank you for taking the time to answer my doubts! I was impressed by how fast I got replies!

You get better temperatures because you're undervolting it at load compared to stock, which is totally fine. When not in a manual overclock, the CPU will follow it's internal voltage requirements, which are quite aggressive.

Doesn't take much at all really. Just reset everything to stock value first to be sure, and then just turn it on. I haven't had any problems since. Trying to manually overclock my CPU caused me nothing but trouble. Its clearly a lot more to overclocking a CPU than it is overclocking a GPU. Its definitely not as straight forward. 

i mean if you want to play around, just do go over 1.3 for the vcore for the cpu under load, and check how far you can go, but as i said for the most part pbo does the same thing that a manual overclock does. 

Yeah you will be better off letting Precision Boost Overdrive handle that for you in my experience, hassle free. And contrary to popular opinion, its not true that you won't see a boost in performance overclocking a Ryzen CPU. According to the video below, you should see a 30%-40% boost in some games depending on how good your GPU is. This is a R7 3700X, but it still proves my point. 
 
 

4.2Ghz is too aggressive for this chip. The boost clock is 4.2Ghz, which translates to the speed of the fastest core, in a single-core workload. You'll never hit that with an all-core OC. You can probably obtain a solid 3.9 or 4.0Ghz all-core OC, but that's about it.
 
Remember, boost is itself an OC. The base clock is 3.6, so anything you get over 3.6Ghz is an OC.

I think I'll just stick to PBO and done... I have a good cooler but I don't want to risk my cpu, things are expensive in my country and with my teacher salary I can't afford to buy a new cpu hahaha

My experience is with Zen, but I've found daily overclocking, aside from fclk/memory to be pointless. The moment your drop a manual voltage in, the system locks it in. which means I go from a 1.1 V average daily voltage to a 1.55 V daily voltage (or whatever I set it to be). That's with C&Q and C-States enabled, mind you. The moment the multiplier is adjusted, it also goes into OC mode and the voltage gets locked there, too. I actually max out the turbo of my 1700X without PBO, so I just leave that off anyways. Makes a bigger difference on Zen+ / Zen2, where the turbo acts completely different.

I would recommend you do it in Ryzen master instead of doing the fixed frequencies through the BIOS, and getting ASUS' motherboard utility to change LLC and that stuff while booted in WIndows. For Ryzen Master, make sure you do it in the manual tab, with it mirrored to all cores of the CCD, or CCX (the little icon to the right of those names should be green). That way it will be on all cores. For longevity, lower the voltage once you found the upper frequency until it's unstable, then go a few notches above the bottom. 
While overclocking the CPU can provide some performance, I would recommend oc'ing the memory more, as I've found that that can provide anywhere from 5fps to 15fps. For that, I would recommend you try lowering timings indivually, rebooting in between to check for stability. Also up the voltage to 1.35v, as that's the XMP/DOCP voltage and therefore is safe. After timings, up the frequency of memory until it's unstable. That should help to get a nice performance gain. LTT did a very nice OC guide for 3rd gen ryzen which goes into a lot more detail. Hope this helps
 

ryzen generally doesn't have a big headroom for overclocking, they are pretty much maxed out, out of the box. 
you can enable pbo and check, usually pbo achieves the same thing that a manual overclock does.