Legacy mode to UEFI mode

[massoccur]

My PC is currently in Legacy mode and I recently purchased an RX 580 from Sapphire which does support both Legacy and UEFI with the BIOS switch, but it's been performing terrible in Legacy. I was wondering what I have to do step by step to get this PC into UEFI mode. I have a 1TB HDD with 100GB partition for my OS and the other 900GB is games, pictures, and all of that good stuff. I know I have to basically wipe the partition for the OS, but would I have to wipe everything else as well? I have an MSI board so if you could give me any help on how to do this, that would be great!

 

[clutchc]

Please list your specs. The exact model board. If it's too old it may not have UEFI. I don't think your performance issue is related to which firmware you are using, but that wasn't your question.

Btw, you shouldn't need to switch "BIOS switch" to legacy unless you have a really ancient board. And are you sure it a "BIOS" switch? Which Sapphire model is it?