It is possible, AMD was the first to come up with the 64-bit extension to x86.. and Intel cloned it, I know that some early Intel x86-64 processors weren't entirely compatible with the AMD64 implementation.
So perhaps OpenBSD is having issues because of that, trying out OpenBSD/i386 would at least exclude that as a possibility.
Taking pictures is apparently one of the only options on modern systems (..without a serial console), so consider doing that.. none of us here are the developers, so try sending an email.
One thing that hasn't came up is bad memory, as a last ditch effort.. try obtaining & running something called "memtest86+", I don't believe this to be the issue but it surely is possible.
http://www.openbsd.org/report.html
http://www.openbsd.org/mail.html