Laptop limited to 300.99mhz, need help to push out max Hz

Hello,

I have an old but good Laptop (Asus ux330ua, bios unlocked) equipped with an i7-7500u and integrated Intel HD620 graphics (pixel clock capped to 300.99 mhz). HDMI output is limited to micro hdmi 1.4.

Im' using an external monitor (LG27UL500 4k 60 hz).

I have tried to improve a little bit the frequency in the resolution of 2160p and 1800p.

This are the maximum frequency I have reached (I'm using the monitor at 1800p 50 hz, 2160p 35hz is too slow).
Timing used are the CVT-RB2. See attachment.

Do you think I can do better and get higher frequency with manual timing? and how?
Really thanks in advance


P.s. The internal monitor works at 1800p, 60hz

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