Because manual OC'ing on Ryzen 3000 increases MULTITHREAD performance at the cost of SINGLE THREAD.
Games are going to be more dependent on one or the other. If some of the games you play are more dependent on single thread performance, guess what's going to happen...
You stopped the cpu from being able to boost to 4.6ghz when it needed it the most.
This is part of the reason manual OC on Ryzen 3000 is so garbage, but people keep doing it anyway, even though it's inferior to the following.
The best performance tweak for Ryzen 3000 is to do 'nothing' to it:
-balanced power plan. High performance does nothing.
-go overkill on the cooling: the better the thermal headroom, the higher the cpu will attempt to boost it's multithread performance towards that 4.6ghz single thread clock.
-ram frequency up to 3733mhz and CL16/17. Then see if you can tighten the timings using Ryzen Dram Calculator.
Yes, focusing on RAM is the most important thing for gaming perf. However, when it comes to Ryzen and ocing it, or allowing it to auto oc, there are ton of caveats and variance.
For me and my R5 3600, i was able to achieve the best thermals, safest operating voltages, and best performance by doing a manual OC.
At stock settings, when stressing my cpu, my SVI2 TFN voltage settled at 1.3v, but my all core oc was only 4ghz. My thermals were were around 75c.
With PBO on and the auto OC settings cranked up, my all core OC would exceed 4.2 ghz, but at the cost of higher vcore, edc, tdc, and ppt. Also at the cost of higher temps. It would throttle itself often too to keep temps down. This resulted in higher benchmarks than at stock settings, but it came with the added cost of performance variance and higher voltages.
With a manual OC, i was able to set my CPU to 4.2 GHz @ 1.3 vcore. My PPT, EDC, and TDC never went past the chips max specs, my vcore ran between 1.287 and 1.3, and i was always at 4.2 GHz. my Temps were around 75c when stressed, and it gave me my highest and most consistent benchmark scores. My single core scores were only about 1% or less behind those achieved with PBO but my multicore went up about 4% compared to pbo( and around 5-10% higher than stock).