Will x86 software run slower on 64-bit Vista?

Do 32-bit applications run in 64-bit Vista just as they would in a 32-bit OS or is a 64-bit system completely different?

For e.g. is it like a case of installing 4GB RAM on a machine that supports up to 8GB or is it like it being a totally different component?

And if it is different, is the difference noticeable? Such as when running Office, or Photoshop...


Thanks for your help.

 

I think there will be some of the 32bit software will run slower on 64bit OS.
But very rare.
Photoshop, Maya, Office and Games are running great on 64bit OS.

 

It's unoticeable.

 

They shouldn't run any slower. 32bit mode on a 64bit CPU isn't an "emulation", the CPU still runs the code natively. The only issue is some redirection of system calls, so 32bit system utilities will possibly have noticeable issues. But you shouldn't have many/any of those.

 

It is noticable if you're using some software which support 64bit and 32bit.
For example:
You have Core2Quad 2.5GHz
8GB RAM
Quadro FX 1700
Software testing = Autodesk Maya

Then, you install 32bit OS(I assume Windows Vista/7 Ultimate).
The maximal RAM you can use will be 3.5GB(due to Ultimate, 3GB for Home Premium, 3.2GB for Business) and the other extra RAM got wasted. So, you will install Autodesk Maya 32bit.
Maya 32bit will only use about 3gb to 3.5gb of RAM due to it is 32bit based.
The computing/rendering/modeling speed will decrease due to less RAM is there.
While if you install 64bit OS(Assumed as Windows 7/Vista Ultimate).
The maximal RAM you can use will be 8GB of RAM(in this example).
So, you won't waste the RAM. You will install Autodesk Maya 64bit.
Maya 64bit will fully use all the RAM you have due to it is 64bit based now.
The computing/rendering/modeling speed will increase due to more RAM is available now.

 

But the 32bit version of Maya running under a 64bit Windows will run identically to the 32bit version of Maya running under a 32bit version of Windows (actually, probably better since the 64bit version of Windows can give it an actual 4GB of address space instead of the 2GB it's limited to under 32bit). That is the point that is being made. You won't lose performance on 32bit apps.

 

YEP! It is the same running 32bit Maya on 32bit OS and 32bit Maya on 64bit OS But, 64bit Maya better than 32bit Maya. I agreed with you.
But it is stupid to have a software which is 64bit supported and install it as 32bit based in 64bit OS.
It is very rare to have 32bit based software run slower on 64bit OS.