Think its just the boot method
on the boot tab, what is showing in Boot mode select? Its on page 51 of your motherboard manual
Since your ssd is formatted as GPT it should just be UEFI
the default is Legacy + UEFI
Legacy would suit your old hdd format, and since your boot drive is in GPT, the legacy boot method would just sit there unable to boot. until it times out and tries the UEFI boot method and starts right away.
Legacy boot method matches MBR. MBR disks have their boot partition as 1st one. Your disk 0 is in MBR, its system partition (system reserved) is the boot partition.
UEFI boot method matches GPT. GPT disks can have boot partition anywhere on drive, your disk 1 is in GPT, its EFI partition is the boot partition.
So a legacy boot method meeting a GPT drive will just sit there going, can't find a partition.
UEFI can boot both since it was created to replace legacy.
What i think is happening is PC tries to use Legacy boot method on disk 1 but after 20 seconds swaps to UEFI and boots normally. Restricting it to UEFI boot method should remove the time.