The xeon e5450 does not support HyperThreading, as far as I could find out.
True, this model has only 4 real cores.
Does anyone know what 'Option ROM Download' is for?
When you turn on a computer (with a standard IBM PC compatible BIOS), the main BIOS will do a scan during the POST (Power On Self Test) boot phase to see what devices are present in the system.
If a device is found, it will be registered (but might be disabled in the BIOS setup).
This is why you have to wait, if you enter the BIOS setup, until all hardware has been registered.
Some devices like SCSI/SATA/RAID controllers, network adapters and video cards have their own Option ROM (with BIOS extensions) which provides additional functionality. The main BIOS will also scan for Option ROM's during POST.
There's allocated, but a limited amount of memory intended for all found BIOS extensions, called the 'Option ROM Space'.
When 'Option ROM Download' is enabled (e.g. for PCI slots), the BIOS extensions from the Option ROM PCI device will be copied (download) to the Option ROM Space.
For example: to boot from a device with an Option ROM or to enter a RAID setup utility, 'Option ROM Download' must be enabled.
64 seems to work better
PCI Latency timer 64 cycles is best timing on XW4600 (Sorry, not tested on XW6600)
12 MasterVerbs with Pulsar 2 @ XW4600 (X38 chipset)