Ok, let me comment on this from a programmer's point of view and give a few insights:
- To make sure your memory is fully used it is important to have a 64bit operating system, if you have more than 3GB. That's correct. Most 32bit systems cannot use more memory because some of the rest is used for adressing, cannot be adressed because you only have 32bit memory adresses and other reasons.
- It is however totally irrelevant whether the application you're running is 32bit or 64bit, unless that application needs to use more than 3GB exclusively (which is highly unlikely in Civ5's case). The operating system will assign Civ5 as much memory as it needs and will rewrite the memory adresses (nowadays NO application can directly access memory), so the OS is the important part, not the game.
- 64bit does NOT equal a faster game which utilizes memory better. Quite the opposite actually. Consider memory pointers. For those of you who don't know anything about programming, a memory pointer is a variable which stores a memory adress. This is used to point to several locations in memory where the real data is stored. Now.. a 32bit application has pointers of size 32bit. That's logical since the pointer needs to store a 32bit memory adress. now.. if you turn that application into a 64bit application you effectively have DOUBLED ALL POINTER SIZES. It's also likely that you have doubled the size of several other numerical variables. This is a big deal and can incrase the memory footprint of this application by A LOT. This could potentially cause a massive slowdown on systems which do not have much memory.
- 64bit Civ does NOT mean it can handle bigger maps more easily. A map is just a datastructure, and those structures usually contain mostly pointers. So if you turn Civ5 64bit you effectively have decreased its ability to handle larger maps, because you have increased the size of those datastructures. I don't have Civ5, but the demo roughly uses 650-700 MB of memory. So even if you think Civ5 needs to be able to address more memory.. what's the point? It's not even close to using more than 3GB. You're absolutely fine with 32bit. Going to 64bit will just increase the memory needed, not decrease it.
- If you want Civ5 to handle memory better, get the programmers to optimize their datastructures and algorithms. That's where the problems lie, not in 32bit/64bit.
- And finally, the usage of multicore has absolutely nothing to do with 32bit/64bit. Both variants can utilize as many cores as they want. First of all there's no system with more than 2^32 processors out there, and secondly the OS assigns the processors to the application, not the other way around, so it again doesn't matter which variant you run.
To summarize: There are certain advantages running on 64bit, but having a 64bit OS is WAY more important than having 32bit applications. As long as memory footprint is something that matters, it is worth sticking with the 32bit version of that application.
