Hp Pro 3405 Series Aahd2-hy Motherboard. i don’t knowwhich motherboard? BIOS up to date?
is the power connected to the 1060? Which PSU?
which CPU?
Is the 1060 connected to the monitor?
reset the BIOS by jumper and try booting with the 1060 again
the lates bios update is from 2014 AMI 8.17is your BIOS version >= F.16 ?
if not, update it:
HP Pro 3405 Microtower BIOS
Free HP Pro 3405 Microtower BIOS. Found 1 file. Select BIOS to download.us.driverscollection.com
should be possible with this system to run a 1060. at least one did get it to work
try the 1060 in a different system