I have the same problem, BIOS recognises BOTH cpus (x5355s) on bios A08, and i have windows 7 ultimate 64 bit, but only 1 cpu shows up on windows? But when i try to revert back to a01, it doesn't let me?
Was Win Ultimate a fresh install if so then I would check device manager to see if you mean that Dual CPUs does not show after doing an upgrading to Windows 7 Ultimate?
The Dual CPUs feature is supported in Windows 7 Professional Edition. Please open Device Manager and expand Processors. How many processor is listed in Device Manager?
If there is only one processor, please upgrade ""Chipset driver"" and then check the result again., look at my other posts for the correct drivers list, also, are you running a 32 or 64 bit system, "control panel - - system" to check, if its 32, it might not pick up the second I would imagine its not meant for dual cpu...
I know for a fact the home premium-> anytime upgrade -> to ultimate works, as would anytime upgrade from any win 7 OS, that's from experience, your best answer would be to upgrade your driver
if no joy there then just fresh install Ultimate
Hope this helps