Cannot boot Older Hardware with Hyperthreading Enabled

Xenserver 6.5 installs, but will not boot. RAM scrub starts and almost immediately panics with final message indicating trap on CPU 0 - NMI 2 with reason unknown.

Disabling hyperthreading enables boot.

6.2 runs without issue.

Cannot provide bugtool output - bugtool from install CD shell bombs with "OSError: [Errno 2] No such file or directory: '/dev/urandom'

Will to gather console output from serial port and add to ticket.