How do I set the default GPU in a multi-gpu system?

[Flux Azreal]

For rendering tasks I have 2 gpus in my system from different brands, while both are in my system I can't seem to see the bios screen, this is probably because it's treating my main gpu as the secondary one and is outputting display into the secondary gpu untill windows starts up, then my primary gpu will get input, I feel like this is the case because in Task Manager it shows that my secondary gpu is GPU (0) and my primary is GPU (1), how can I fix this? Oh and my primary gpu is connected to the top-most slot (cpu) and the secondary is connected to my lowest one (chipset) i'm using the Asrock Ab350 pro4

[Applefreak]

48 minutes ago, Flux Azreal said:

For rendering tasks I have 2 gpus in my system from different brands, while both are in my system I can't seem to see the bios screen, this is probably because it's treating my main gpu as the secondary one and is outputting display into the secondary gpu untill windows starts up, then my primary gpu will get input, I feel like this is the case because in Task Manager it shows that my secondary gpu is GPU (0) and my primary is GPU (1), how can I fix this? Oh and my primary gpu is connected to the top-most slot (cpu) and the secondary is connected to my lowest one (chipset) i'm using the Asrock Ab350 pro4

You can set the primary gpu in bios. Usually found under advanced options, look for an entry boot from PEG (Pci E Graphics) to select the primary device. In windows, the card that has the output or to be more precise display number 1 on it, will be primary.