@alegasalv Is the gpu_mem actually using the 512mb though? I found that enabling the 'hdmi_enable_4kp60' overrides the setting, as running 'free' in the terminal was showing less than 512 being used. It's only meant to boost the stock gpu memory by 50mb's...or so I've read.
I have mine set at:
force_turbo=1
over_voltage=8
arm_freq=2147
gpu_freq=750
gpu_mem=512
Needed to force_turbo in order to go above gpu_freq=550 though, tested by running 'vcgencmd measure_clock core' to confirm. Also, 'vcgencmd measure_clock arm' for the cpu.
edit: Forgot to mention...if raising the gpu_mem, then using the raspi-config gui to modify anything, it will automatically hash out the hdmi_enable_4kp60 on you...or at least it does for me. I guess it's anything over a certain value.
edit2: Sorry...also forgot to mention that in order to use the gpu_mem=512, you need to enable cma=512 as well. The kernel crashes on me otherwise.
dtoverlay=vc4-fkms-v3d,cma=512