You definitely need a terminator on both ends of the cable; SCSI wants that.
The card in the PC is the Host Bus Adapter . It should normally stay on ID 7. There is often a built in termination on the HBA, so you only need a terminator on the dangling end of the SCSI bus.
The hard disk will stay off until the HBA sends a command to reset the bus and probe it for devices. That's why you hear it spin up much later after you've turned on the PC. That's pretty normal. Yeah, it sounds like a jet engine.. imagine back in the day when there were rooms full of those, and much bigger too
The PC powering off is likely a voltage problem, the motherboard or the PSU senses high current/low voltage and shuts down. There could be a problem on the board or hard drive that needs repair or toss it...If you can, try to shed some load (i.e. unplug stuff and remove cards you don't need until only the 1 SCSI board and hard disk is powered up. You can even unplug the power on your main hard disk, for a test, since you are in the BIOS and you don't need to boot just yet.