My previous motherboard seems to have died a few days ago (non-ASUS), which is kind of a bummer, but kind of fine, given that the MB and CPU were 11 years old. So I bought an AMD Ryzen 7 7700x and an ASUS "B650-Plus WiFi" to replace it. I tried getting it set up yesterday but have been encountering various problems. I updated to the latest BIOS today and it hasn't solved anything.
1. First, I have an evga GTX 460 (it's old, I know). I have 2 monitors plugged into my GPU, the primary is DVI (and DVI only) and the secondary is HDMI. The MB lights the white VGA LED if I have my DVI-only monitor plugged into my card on boot. I can hot plug it after boot though. Why? I have to boot with my 2nd monitor plugged into the MB's built-in HDMI.
2. The BIOS does shows all of my drives (three HDD, one SSD). But for whatever reason, it won't allow me to boot into my Linux SSD. That OS install / SSD has nothing to do with "UFEI" or "GPT" or whatever. I do have a Windows 10 install on one of the HDDs, and it'll allow booting into that (when it even recognizes it on boot anyway). I use that maybe once a month for random things. My main OS is on the SSD, and it's Linux. My searching leads me to believe that I need to enable "CSM" in order to boot from non-UEFI configured drives. However, when I enable that setting and hit F10 to save and reboot, the BIOS LED on the MB is green and I get no video feed and have no choice but to short the CMOS pins to reset my BIOS settings. That's without changing any other settings, simply enabling CSM.
3. I tried removing the GTX 460, but then I can't enable CSM. When I googled, I found things that said you can only enable CSM if you have a discrete GPU. I am not at all certain why I would need a discrete GPU in order for the MB to boot into my Linux SSD. Those concepts seem completely unrelated. Maybe I'm missing something.
4. This is not a big deal, but, why is CSM not available if resize BAR is on? I guess I don't need this, since I won't be gaming, but again, what does the discrete GPU situation have to do with booting an MBR disk.