alright heres some interesting info
the nvram variable to disable HT, does so at a firmware level and works in all OS as a result, whats interesting is, when I set the NVRAM variable and rebooted, instead of the MP doing a normal warm reboot, it fully shut down with a Click of the Relay, then clicked back on, exactly like what happens during a BootROM update
in fact it disables it so well, that Hwinfo64 cant tell the CPU supports HT
(Hwinfo64 will normally show the feature as Red if its supported by the CPU but disabled by something)
and heres my CPU-Z validation
http://valid.x86.fr/j0xr1z
speaking of CPU-Z validations while validating my MacPro5,1, in the recent validations I spotted a Dual CPU X5675 MacPro5,1 running BR 144, but a GTX 980 Ti IIRC, I wonder if that was anyones Mac Pro here?