if the program was originally downloaded in 32bit and there is a 64bit version you will need to download and install the 64bit version to run it in 64bit mode.
as you know 32bit programs will run on a 64bit os but not the other way around, but if you have installed a 32bit program nothing can make that into a 64bit program except downloading it again in the 64bit version.
x86 is an instruction set that was first used with a 8086 cpu many years ago (early 80's i think.) and was 16bit originally i believe but the later 32bit cpu's used the same x86 instruction set, the instruction set for 64bit cpu's is x86_64 or amd64 because i think amd were the first to introduce a 64bit cpu the athlon 64 anyway the x86_64 just got shortened to x64, so that is why you have x86 being 32bit and x64 for 64bit operating systems.
now not being a steam user i couldn't tell you for 100% sure if the folder name you install the games into makes a difference or not, but i'd assume you could name it program files (x86) or program files (x64) or tomdickandharry and it would make no difference whatsoever, so if steam doesn't check what os your running and download the correct version for your os and you have been manually choosing the 32bit or x86 versions then like i said earlier you will need to download and install the 64bit versions if you want to run it with the full capabilities of your 64bit os.
Then why do they bother putting the X86 or X64 after the program files if it doesn't matter anyway?
it is the windows os that creates the program files (x86) and program files (x64) folders, it does this really just to help the program writers know where they can safely install their programs to and have them work, it also helps the user know if they have a 32bit or 64bit program installed, like i said the folder name of where a program is installed into really makes no difference to the os just as long as it knows where to find and run it with the correct instruction set x86 or x64.
probably another reason is so you can install the same program in both 32bit and 64bit versions without having things get confused.
a better explanation is here :- .http://www.howtogeek...les-x86-folder/
Edited by terry1966, 01 May 2015 - 08:27 AM.