Bios Mods -The Best BIOS Update and Modification Source

I have a piece-meal computer based off a Dell XPS 8900 with a;
Dell. Inc 2.1.8 2/24/2017 EUFI BIOS
SMBIOS Version 2.8
Dell Bios Download link: http://www.dell.com/support/home/us/en/1...erId=4YGRR&fileId=3646886473&osCode=WT64A&productCode=xps-8900-desktop&languageCode=en&categoryId=BI
Intel I5-6400

Would if possible like to figure out how to unlock the BIOS to allow for overclocking of the CPU and iGPU.
Very new to the BIOS modding concept.

Any other info needed?

Thanks for any and all help

Please someone, I'll throw some money in a paypal for beer funds.