Question Ryzen 2600 - 3.75gh

I want to get my CPU to at least 4gh, but so far I've only been able to reach 3.975. It's starting to feel like I've hit the ceiling seeing as I've pushed it to 1.3500v. Granted, I'm happy that I was even able to push it this high, but I've seen other people push it to 4.1 and be stable on air so I was wondering if anyone had thoughts on how else I could approach it. (I'm a noob at overclocking).
 
The Bios won't let me past 1.3500v. I just found out about Ryzen Master and it got me up to 4gb bypassing the bios' 1.35v limit to get me to 1.45v but any lower than that and it's unstable and my temps are too high for my liking at 4gh 1.45v (around 75c) right now (I'm sadly using the stock cooler). 3.975 is a hell of a lot better than 3.4 so I guess I'll stick with that until I can afford better parts.