OK. You have confirmed that you cannot use your USB hard drive with OpenBSD, whether -release or -current. I'd missed your comment in post #13 that inserting a USB flash drive causes a reboot. With that additional knowledge, we now know that the problem is related to your USB subsystem, and not your USB hard drive. But it was suspected, because your mouse detaches.
In my view, these are your primary options. I've color coded them, based on my assessment of your posts on this forum. You will have a different view of your own skills or interests, of course.
Green. I believe you are capable of this option.
Blue. I believe this option is possible for you, but would require new skills and additional effort: engaging directly with developers and applying any recommended patches you receive.
Red. I believe this option is beyond your current skills.
- Use another OS. You have already learned that other BSDs work, and you could choose one of them instead of OpenBSD.
- Replace hardware. For reasons not yet determined, OpenBSD does not correctly operate USB on this mainboard. Swap this component or the system for another.
- Install onto the drive from a different system. This is unlikely to solve your problem. But if you successfully install onto the drive on another system, and boot it on this "broken" system, you would have isolated the problem to the RAMDISK. And successfully circumvented the USB problem. Improbable, but not impossible.
- Install on an internal hard drive. This would provide you with a full OS, with a (likely) nonfunctional USB subsystem. This is not the USB-based system you want, but it would allow you to engage with the Project to debug the USB subsystem.
- Use a serial console. The addition of a null modem cable and a second workstation to operate it would allow you to engage directly with Project developers for support of this inoperative system.
- Configure a diskless(8) system. OpenBSD can be booted from a network and operate without any disks at all. As with the hard drive option above, this would permit you to engage with Project developers to debug the USB subsystem.
I'm sure there are other options as well.