I play crysis 2 everything on ultra, HD resolution texture packs, DX11, fullscreen at 1080p.

- 4 GB G.Skill ripjaws X ram

I don't know much about Crysis, but this might be the problem.

What do you mean that might be the problem? I thought that 4 GB of ram was good enough for any game really

It looks like your probably low on memory. Best thing to do here would be to buy an additional 4gb of ram which is best done if you get the exact same model as your current 2 sticks. That will most likely fix the problem and if not you could experiment with overclocking. For the cpu and memory do all your edits from the BIOS as that gives you the most control and for the gpu use either MSI afterburner or ATI catalyst. Both provide very similar functions. But before you try any of this get more memory first because overclocking can be dangerous!!!

experiment with OC'ing eh? Yeah, ive done it be4.. and its not *that* dangerous. I've even overvolted my gpu to the max which is by default a locked function in afterburner but you can do it . and also that didn't really solve my freezing problem when i played it again after doing it. After it crashed crysis from overclocking too much, I decided to then on utilize benchmarking programs not to benchmark, but to find stability in my overclocking to get it where i need it.

Oh and also about more ram, theres a problem.. My cpu air tower is so big, it actually covers 2 of the ram slots effectively leaving me only with 2 available. Its not the tower itself, but the fans attached to it. Its the corsair A70 cpu tower.

Oh one more thing.. the motherboard i got, it overclocks to 4.2 GHz with a press of a button, so that will be easy if i decide to do this.

I meant more like overclocking can be dangerous if you don't know what you're doing but you seem to be quite skilled in this. For me it is very dangerous when I mess around with my memory clock multiplier ratios because if I don't increase the voltage sufficiently the computer will crash instantly and won't turn back on. The only way to fix it is to reset the bios setting which is a hassle.

And for the ram, these days 4gb often isn't enough especially if you're running games such as Crysis 2. Because of issues with the cooler's size you have two primary options for upgrade. One you could buy a new cooler in which I would recommend one from xigamatek because they are quite effective and take up little room on your mobo (note: they are very tall so check your case size to make sure it'll fit). After that you could then buy an additional 4 gb. The downside is that not only will you be getting rid of your current cooler (something I always hate to do with perfectly functioning hardware) it is also probably the most expensive option. Second plan is that you could buy a pair of 4 gb sticks and put those in place of your current two giving you 8 gb total. An advantage here is that if you later decide to change your cooler, you will have 2 more available slots for future use (16 gb anyone  ). The issue though is that you would still be retiring your once again perfectly functioning 4gb of ram.

A lot of it is caching, I believe. RAM is much faster to access than Disk, so games store as much information in RAM as possible in a sort of pseudo-cache. Those sort of CPU intensive games also tend to store massive lookup tables to improve the speed of gameplay.

I don't know what kind of information is stores in RAM (other than the local player/mob data and the current map), as that tends to be very game dependent. I haven't done a whole lot of research into the CryEngine used in Crysis 2, but I am aware that they took a lot of shortcuts (as expected).

Here's some information that I came across awhile ago that might interest you.

http://http.developer.nvidia.com/GPUGems3/gpugems3_ch16.html

A Flash drive is not a good way to see how an SSD would behave. USB is slower than most HDDs.