i7 4790k OC & stock – huge performance difference between default power settings VS increased power limits

I have a secondary PC – an HTPC with a 10 year old i7-4790k cpu (stock 4.0Ghz with 4.4Ghz turbo, undervolted to 1.1v), paired with an RX6600. I am playing around with it to boost fps in games.

With my current stock speeds and undervolted stock speeds, I get about ~7000 in passmark. For reference, the average 4790k on passmark gets closer to 8000. I tried to manually overclock it to 4.6GHz @ 1.19v and everything else on default/auto, and I got maybe 7500 in passmark. Both this manual OC and stock speeds gets me around 40-70 fps (averaging around 50s fps) during intensive scenes in Silent Hill 2 remake.

My motherboard has a BIOS AutoOC function that sets the clockspeed at 4.6Ghz boost. I set the voltage to 1.18v. This autoOC result gets me a massive ~9000 ~9200 in passmark. This autoAC also massively boosts my fps from a 50 fps average to around 75 fps average in the same scenes/same areas in the Silent Hill 2 remake.

It turned out this was caused by the default "auto" settings that limits power to 88watts. I tried my undervolted near-stock stock speeds settings with power limited increased from auto/88w to 120watts – and now get ~8500 in passmark. I manually overclocked to 4.6GHz with power limiter increased to 140watts – and get ~9000 in passmark, the same as my auto OC to 4.6GHz.

So basically, I was going from ~7000 to 8500 in passmark scores by keeping the same stock speeds but increasing the power limit from auto/88w to 120w. This is a 21% increase in performance without even changing the clock speeds.

Strangely enough, I checked both HWInfo and HWmonitor power consumption for the cpu package and for cpu cores, and they showed the difference between the auto/88W and 120w power settings wasn't that much. It was maybe 10-15 watt difference (eg. if the auto/88w setting was 115w, the 120w power setting would show 125-130w).

Thus, can anyone explain why there is such a huge difference (eg. 21% even without overclock) just by simply increasing/adjusting the power limiter from default? Why did my stock/default 88w "auto" setting used by my motherboard nerf the 4790k so much?

Is this normal among many motherboards or did my motherboard set uniquely bad settings that nerfed my CPU?

Passmark scores:

~9000 with BIOS autoOC to 4.6GHz and power limit is determined by the autoOC setting

~7500 with 4.6GHz OC and power set to auto/88watts

~9000 with 4.6GHz OC but power set to 140 watts

~8500 with 4.0GHz/4.4GHz boost but power set to 120 watts

~7000 with 4.0GHz/4.4GHz boost and power set to auto/88watts

Sscreenshots of passmark score with autoOC:
https://imgur.com/a/0nk6VIW

Specs:

i7 4790k (delidded)

GIGABYTE GA-B85M-D3H motherboard

16GB DDR3 RAM @ 1600MHz

500 GB SATA SSD