Sajin
It may/may not work. For best compatibility buy a motherboard that uses uefi.
Thanks Sajin.
I saw some videos on Youtube with reviewers testing RX480/GTX 1060 with 6 years-old motherboards (not sure if the MBs had UEFI but the processors were contemporary to mine). Other than lower framerates compared with modern processors, everything ran fine.
In the HP forums (like my system), the GTX 9xx series are a hit-and-miss... For some people everything works fine, for others doesn't boot.
I'll probably wait a little more until more experiences, or until I buy a new system.