how can i turn off 32-bit compatibility in win 7 -64

As far as I am aware this isn't possible.

I think mainly because although 32 bit apps aren't running natively, they aren't running in some sort of heavy duty compatability mode.

This would be much the same as trying to turn off 16bit apps in Windows 7 32bit, you can't.

It's just a different kind of process and as long as there aren't any 32bit apps running your system performance should be without 32bit hinderance.

Of course I'm no expert in this field so if I've got something majorly wrong feel free to correct me and give me a good telling off (but I'm sure that won't happen!).

Oli

What osholt said is pretty much right.

You'd see no difference if there was a way to disable the 32 bit emulation in 64 bit Windows. It only "kicks in" when a 32 bit application is executed.

There is zero emulation going on, unless you are on Intel's Itanium processors (not likely, Itaniums are very expensive server processors.) All that happens is a switch of the processing mode on the processor for x86 instructions versus x86-64 (called Compatibility mode.) You cannot turn this off, nor would you want to, or need to. There would be zero increase in performance even if you found a way to turn it off.

Way I've understood it to work is in Vista and 7 64, 32 bit applications run on top of WOW64, which is 32 bit emulation layer, which intercepts the calls made by 32 bit applications to the OS, and converts the 32 bit data structures in to the 64 bit aligned structures.

nutpantz said:

...then why did M$ drop 16-bit program capability?

DOS 16bit support. This was dropped because there is no way to support DOS without extensive emulation when the processor is running in "Long" mode. The processor must be switched to "Legacy" mode which requires a hard reset. Also for the fact that 16 bit applications are now mostly rare.

See: x86-64 - Wikipedia, the free encyclopedia

Operating mode explanation

The architecture has two primary modes of operation:

Long mode

The architecture's intended primary mode of operation; it is a combination of the processor's native 64-bit mode and a combined 32-bit and 16-bit compatibility mode. It is used by 64-bit operating systems. Under a 64-bit operating system, 64-bit programs run under 64-bit mode, and 32-bit and 16-bit protected mode applications which do not need to use either real mode or virtual 8086 mode [DOS apps requires real mode and virtual 8086 mode] in order to execute at any time run under compatibility mode. Real-mode programs and programs that use virtual 8086 mode at any time cannot be run in long mode unless they are emulated.

Since the basic instruction set is the same, there is almost no performance penalty for executing protected mode x86 code. This is unlike Intel's IA-64, where differences in the underlying ISA means that running 32-bit code must be done either in emulation of x86 (making the process slower) or with a dedicated x86 core. However, on the x86-64 platform, many 32-bit x86 applications could benefit from a 64-bit recompile, due to the additional registers in 64-bit code and guaranteed SSE2-based FPU support, which a compiler can use for optimization. However, applications that regularly handle integers wider than 32 bits like cryptographic algorithms will need a rewrite of the code handling the huge integers to take advantage of the 64-bit registers.

Legacy mode

The mode used by 16-bit (protected mode or real mode) and 32-bit operating systems. In this mode, the processor acts just like an x86 processor, and only 16-bit or 32-bit code can be executed. 64-bit programs will not run.

(and if there was no difference is performance of the 2 why do 32 bit bench marks have diffrent results than 64 bit benchmarks in win 7-64 i would think the difference would be the 32 bit mode)

You are speaking of difference performance there. 64 bit applications have the ability to run faster because they can take advantage of the additional registers in the CPU as well as crunch larger numbers faster. A 32 bit application cannot do this, compatibility mode or not.

nutpantz said:

In Windows Server 2008 R2 Server Core, it's an optional component. WoW64 is designed to take care of many of the differences between 32-bit Windows and 64-bit Windows, particularly involving structural changes to Windows itself.

its the
In Windows Server 2008 R2 Server Core, it's an optional component

that make me think you can turn it off
WoW64 - Wikipedia, the free encyclopedia

note the In Windows Server 2008 R2 it says nothing about windows 7, i wouldnt go taking Wikipedia as gospel either... its not unheard of for it to be wrong