Are there any motherboards that support 4 physical CPU's? AAnyhow, it only supports 2 physcial CPU's.
PCs with multi-core processors:
Windows 7 was designed to work with today's multi-core processors. All 32-bit versions of Windows 7 can support up to 32 processor cores, while 64‑bit versions can support up to 256 processor cores.
PCs with multiple processors (CPUs):
Commercial servers, workstations, and other high-end PCs may have more than one physical processor. Windows 7 Professional, Enterprise, and Ultimate allow for two physical processors, providing the best performance on these computers. Windows 7 Starter, Home Basic, and Home Premium will recognize only one physical processor.
I would lean for the same answer as shanky887614. From what I gathered, W7 Ultimate is limited to 2 sockets (but no mention on # of cores) so anything above that would require Windows Server license. There is also a limit on RAM based on the Windows edition (Starter = 2GB, HP = 16GB and the other are limited to 196GB).
starter, home basic, and home premium support 1 physical processor. professional, enterprise, and ultimate support 2 physical processors.
32 bit versions support up to 32 logical processors. 64 bit versions support up to 256 logical processors.
EDIT: the only boards you're going to find that support four physical AMD processors are going to be server boards (opteron) in the $800+ range, and you'd have to invest in a server operating system to utilize them.