I'm having Intel(R) Pentium(R) 4 CPU 3.00GHz Processor with 2GB RAM. While trying to install Windows 8.1 Pro 64-Bit i gave me an error saying that the processor is not compatible with Windows 8.1 Pro 64-Bit .I checked the system requirements and found that my processor doesn't support PrefetchW but all the other requirements are supported.

HTT * Hyperthreading enabled

X64 * Supports 64-bit mode

NX * Supports no-execute page protection

PAE * Supports > 32-bit physical addresses

SSE2 * Supports Streaming SIMD Extensions 2

CX16 * Supports CMPXCHG16B instruction

PREFETCHW - Supports PREFETCHW instruction

Note : '*' means it's there(supports) and '-' means it's not there(doesn't support)

I know i'm asking a poor question. But i want my old processor to run Windows 8.1 64Bit anyway. Is there any way to run Windows 8.1 64 bit without PrefetchW support?

  • You could try to disable superfetch/prefetch ==> tomshardware.com/reviews/ssd-performance-tweak,2911-5.html – whs May 1 '15 at 2:12
  • @whs My processor does not support prefetchw – CodeIt May 1 '15 at 3:28
  • I know. That's why I suggested to set it off in the OS. However, I am not sure whether it will let you install the OS in the first place. – whs May 1 '15 at 3:59
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    If it is an option superuser.com/questions/831394/… looking at the web the 3 items PrefetchW & LAHF/SAHF & CMPXCHG16B effects the 64bit OS versions. From what i can tell so far, the 32bit OSes do not have that problem. – Psycogeek May 1 '15 at 4:23
  • @whs I'll try and will give an update. – CodeIt May 1 '15 at 5:05

no, this is not possible. The only way to install Windows 8.1 on this CPU is to use the 32Bit (x86) Version which is recommend when only using 2GB of RAM.

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