4Ghz on anything besides a 1800X or 1600X is rare. Typically all Ryzen chips top out at 3.9ghz.
So some people say a max voltage of 1.4v is good, but AMD officially states for 24/7 overclocks 1.35v is a good number. (But they also say you can push 1.45v and be safe for benchmarking purposes only.)
I personally go inbetween that number, if you stay below 1.39v you are good. Plus, an H100i cooler can't really handle a Ryzen 7 at 1.4v.
I personally run my Ryzen 7 1700X at 3.8ghz at 1.369v (getting to 3.9ghz on my chip takes way too much voltage, let alone 4ghz). Temps top out at around 75C on a H100i V2 with ML120 fans.
However you might have a golden chip, so I'd start with 3.8ghz at 1.35v. Then download OCCT stress tester, run that for 30 minutes. If it passes, try 3.9ghz.
Then once you hit the frequency that is best, start lowering the voltage. Run OCCT every 15ish minutes to check voltage. If you get instability, then increase voltage to last previous stable voltage and follow instructions below.
As far as temperature limits, you want to stay in the 75C range or lower, I'd say if you are pushing voltages beyond 1.35v, try to stay below 78C.
Then once you have your desired overclock, you want to do a LOT of stress testing. Here's the rundown
A. For monitoring software, use HWINFO64. It reports the proper voltages for Ryzen which will be (SVI2 TFN).
- 8 Hours of Prime95 blend
- 8 Hours of RealBench
- 8 Hours of OCCT (optional)
However, this is all assuming your memory is stable in the first place. Setting your RAM to 3000mhz to "be safe" means nothing (no offense). Because your memory controller might not even be able to run 3000mhz RAM, as is true with some ryzen memory controllers running on stock SOC voltage.
So first, you want to absolutely insure you have your memory stabilized first.
- Set your RAM to its rated 3200mhz speed and its rated timings, or just enable XMP/AMP/DOCP.
- Download memtest86, Prime95, and realbench.
- Run memtest86 (free version) at its default config. Takes 4 hours normally.
- Run Prime95 with MEMORY INTENSIVE config for 8 hours. Memory intensive config is 1. 512k on min FFTs, 2. Half your memory in memory usage (so 16GB would be 8192mb). (But you need to disable AVX, as AVX instructions on this program are so taxing on the CPU it isn't what you see from the real world. Go into the P95 folder, go to the local.txt and set AVX=0)
- Run Realbench for 8 hours.
If you do NOT double check that your CPU can run your memory at its rated frequency with full stability, then overclocking your CPU is going to be a nightmare. You can encounter errors no matter how high you set CPU voltages or frequency, because the memory wouldn't be stable in the first place.
Let me know if your memory fails or not, if it fails the tests then we can try a few things. 