Why can’t I get more than 60 FPS in CS:GO

(I have rectified my answer. To clarify: every process gets 2 GB of virtual address space. All processes combined can't exceed 4 GB of physical memory)

Actually, yes. There are many misconceptions about the memory limit in 32-bit Windows OSes.

First of all, when I say RAM, this includes every kind of RAM. So not just regular, but also your video RAM. Only physical memory though, not swap/paging.

The maximum available amount of RAM per process for a 32-bit OS is 2 GB. If you have a 64-bit OS, a 32-bit process can allocate up to 4 GB.

Additionally, the entire OS can only address 4 GB for every process combined, while 64-bit OSes can allocate 8 TB.

Also interesting is that this limit adds up to the paged pool. This means that a 32-bit OS cannot use more than 4 GB total, which means 6 GB for all applications including virtual memory. Of course, this has nothing to do with RAM, because the other 2 GB would be stored in the paging file, limited to your hard-drive's speed.

For more information, see Memory Limits for Windows Releases.

I don't know about a comprehensive guide, but I have a few suggestions.

First, as background, every setting is going to be geared towards balancing two different (and diametrically opposed) optimizations--that of speed in calculation, and size in memory. For instance, your texture quality, and to a lesser extent, model quality, will have a large memory usage with relatively minimal processing imprints, whereas your physics, shadows, and reflections will be rough on the CPU/GPU but in some cases have absolutely microscopic memory footprint. I'll call this Speed vs Size.

Your Size-heavy settings are going to increase load times between levels and eat up RAM, which would slow down other processes, but we'll assume you're running SC2 by itself. Your Speed-heavy settings are going to affect your FPS the most, and also have the most wow-factor.

So with that in mind, whenever I have to turn my graphics down because I'm playing tug-of-war (I usually run on Extreme:D ) I default everything to medium and then turn texture quality to high, shaders to high, reflections off, particle effects to low, physics to low, and Model Detail to high. If you hover your mouse over each option it will detail out what it does, and you can usually tell whether it will be more of a Speed sacrifice or a Size sacrifice, and if it's not clear-cut it's a mix of the two.

I did a test to show the difference, this is a shot of a replay on ultra, and this is a shot with the above settings. I started the match with about 80 fps on ultra and about 130 on the frugal settings, and around this point (tons of marauders, roaches, marines, and carriers) I was running around 40-50 on ultra and around 60-70 on frugal. As you can see, there's not a whole lot of difference in the stills, but it was noticeable enough--you can see the lack of motion trails on the interceptors, for example, and some of the explosions weren't as spectacular.

You shouldn't have a problem with that machine, but if you do, you can try these settings as a starting point, or try setting the various Speed settings even lower. You probably won't have to put the texture or model quality lower, as in general that will just affect load times and not so much the calculations.