I recently noticed that my BIOS was running in legacy mode, and I wanted to switch it to UEFI mode because I originally thought it already was and I've read that it's better. So first I converted my HDD from MBR to GPT using the windows MBR2GPT tool and that worked fine. Then I went into my bios to look for the legacy/uefi setting, but my motherboard(ASRock AB350 Pro4) doesn't have an exact setting called that. The closest I could find was and option to disable/enable CSM. I read that CSM made the UEFI looks like a BIOS so it could boot from a BIOS OS, and that you should disable it if you are running windows 8 64 bit UEFI or higher, which I am, and now that I had converted my OS from MBR to GPT making it able to boot from UEFI, I disabled CSM. Everything worked fine until I went to play some games and noticed my FPS was significantly decreased. I have a 1050 Ti, and I went from 220 FPS in CS:GO to 30, and from 45 FPS in War Thunder to 8. I restarted, enabled CSM, and the FPS went back up to what it was normally at. Why would disabling CSM, which you should disable if your OS is UEFI and if you are on a newer OS, hurt your GPU?
Specs:
Ryzen 3 1200 @3.9 Ghz, @1.3V
ASRock AB350 Pro4
1TB Toshiba P300 HDD
Corsair CX550M PSU
Zotac 1050 Ti Mini
8GB(2x4) Crucial Ballistix Sport LT RAM @2800 Mhz
Windows 10 Pro 64-bit
Specs:
Ryzen 3 1200 @3.9 Ghz, @1.3V
ASRock AB350 Pro4
1TB Toshiba P300 HDD
Corsair CX550M PSU
Zotac 1050 Ti Mini
8GB(2x4) Crucial Ballistix Sport LT RAM @2800 Mhz
Windows 10 Pro 64-bit