[zeusk]

Exactly my thoughts. He builds a "custom" computer, mix matches parts but is unaware of the difference between CSM/UEFI or MBR/GPT?

UEFI and GPT have been on the scene since Vista (2007).

[cbmuser]

Assembling a computer from parts doesn’t really require in-depth knowledge these days thanks to true plug’n’play.

No jumpers to set for CPU multipliers, IDE master/slave or IRQ/DMA/IO etc.

[zeusk]

MBR/GPT and BIOS/UEFI aren't anywhere in-depth as clock multiplier, bus master/slave or IRQ/DMA/IO.

MBR/GPT and BIOS/UEFI along with SecureBoot are neatly explained in the UEFI and motherboard manuals. Also custom parts imply you're running XMP memory and need to enter UEFI to enable the advertised clocks anyway (Hello! JEDEC).