onboard Realtek audio cut out

i'm experiencing an audio cut out when i'm playing at unlocked frame rate.
but when locked at 60 fps. my audio is just fine, no cut out, no stuttering.

but also everything is fine when i'm using a bluetooth speaker even my frame rate reaches 100+ fps.
i have tried every solutions i can find from the internet, but none of them have worked so i don't know what should i do now.

my motherboard is an H370 Performance with Realtek audio chipset.
the problem shouldn't be my speaker (Kenwwood omni A5) because this also happens with my earphones.

this is also happens to every games i'm currently playing.

things i have done:

-fresh install of windows 10
-uninstalling audio driver and let windows install a new one after restart
-installed High Definition Audio Device driver
-installed Generic Audio Device
-Disabled audio enhancements
-changed Default Format (sample rate) everything from 24bit 48000Hz to 16bit 44100Hz
-Configure Speakers and unchecking Full Range speakers
-installed a modded realtek drivers.

PC quick specs:

i5 9400f
H370 performance
16gb ram
rx 580
seasonic s12ii-520 evo