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How to update Lenovo G570 bios in order to install Windows 10 in a GPT disk?

I have used both Win8.1 and Windows 10 before on the same laptop so I know it supports UEFI. However, I can’t see the option to enable it under the Boot options menu in my Bios settings. I have tried mbr2gpt tool but UEFI firmware settings don’t show up in advanced settings after troubleshooting.
Do I need to flash the BIOS? I have currently installed Win10 on a MBR disk. Are there any cons to having it installed on MBR partition instead of GPT partition?