Do I **need** increase my RAM?

Solution
The programming of the game opens it to be able to load more into DRAM and then draw directly from it, also the rest of your system is using DRAM (OS, start up programs, background services, etc) so with 8 more is free for other things, some interesting stuff here:

http://www.corsair.com/us/blog/bf4-system-ram/


Good question... Im trying to figure out that... Since I have a PC gamer, is it all about shorter loading times? higher fps?

 
More ram will not decrease loading times at all. Unless you are playing games that are known for sure to use more than 4gb of ram, then you won't see any fps increase. However, you will see more speed when you are multitasking
 


Im planning buying BF4, but what if I dont care about multitasking?? I think just Origin and Steam open while I play wont require that upgrade...

And like you I have a 280X Sapphire Vapor-X =)

 
The programming of the game opens it to be able to load more into DRAM and then draw directly from it, also the rest of your system is using DRAM (OS, start up programs, background services, etc) so with 8 more is free for other things, some interesting stuff here:

http://www.corsair.com/us/blog/bf4-system-ram/
 
Solution


So while playing BF4 (ultra settings) about 40 minutes I got these measures using MSI Afterburner:

GPU temp: 71°C
GPU usage: 99%
CPU 1, 2, 3 and 4 usage: 100%
RAM usage: 3951Mb