   Multiple CPUs and capabilities (can they be mismatched?)
  Is it possible for a system to have two CPUs which are mismatched in terms of functionality? For example, a dual Athlon64 (not dual core) where one is a Winchester core 3200+ and one is a Venice core 3200+? The latter has SSE3 while the former does not. And if such a situation arises, how can I deal with it robustly? Does Windows provide stuff to query the capabilities of a specific CPU, or do I need to spawn a thread with an affinity for each CPU and run cpuid checks from all of them? And then do I need to always know which CPU I'm running on? (Obviously I'd be writing multithreaded code here.)   
  If this were the case it would break an enormous amount of software, the OS would have to fixed the entire process to a single processor or disabled the partially supported instruction set. So while it may have happened once or twice as a bug, I wouldn't bother supporting it.Of course it's commonplace to mix processor types or even architectures on mainframes, but that's by design and everyone's aware of it.   ;  I would be highly suprised if a dual-cpu desktop system worked with two different processors. And if it did somehow work, I would bet that the mobo/bios and windows would have a hell of a time running on it, because it probably isn't one of those things that they coded for.   ;  I saw a post once just recently from a guy that did this.  The first time he tried it he got a POST error like "mismatched CPUs" and it would not continue.  He then swapped the CPUs and it booted, but the system thought it had SSE3 but it didn't.The behavior I suspect would depend on the BIOS.;  Are you an idiot? venice and winchester cores are not designed for MP.;  imagine a heterogen cluster ... there you have your multiprocessing system with different cpus...this kinda tricky situationhow do you find out if a processor supports sse3 and other instruction sets ...maybe you can call these routines parallel on all systems and setup the programm in an other manner for every process ...with MPI or openMP this could work (using private variables ... etc. )   