I was planning on upgrading to a i5-2500 and 8GB of DDR3 ram (along with a suiting mobo too) but i don't know if this would actually boost my performance as much as just getting another GPU (say GTX 560 or 580).
My main goal is to be able to run TERA online on max settings at 1920*1080, I recently played the first beta and i noticed an overall good framerate, but it dropped in crowded areas. Unfortunately, game's closed for now so I cant run benchmark testings with it...
From what I have read, the TERA Online game is bottlenecked mostly by the graphics card when there are not many players around and by the processor really badly when there are a lot of players around.
If you did indeed beta the game and saw your FPS was low with lots of players and good enough with only a few players then I would just go for the 2500k and a regular gigabyte z68 motherboard and CT2KIT51264BA1339 RAM.
That being said, I don't know that you can keep all the settings maxxed all the time (especially not Anti-Aliasing) with just one upgrade or the other. You may have to upgrade both sides to have max settings all the time.
I agree with Raiddinn. Slowdowns only with lots of other characters / mobs around points to a weak CPU. Make sure you have a strong enough, quality PSU to support whatever upgrades you are contemplating.
Also, on the CPU, any noticeable difference between the i5 2500 and 2500k? I've read that overclocking on the 2500k is better (although i really don't plan on overclocking, at least for now) they have a ~30USD difference in Amazon, also, id have to pay taxes in my country if i ordered the 2500k version (since it is above 200 dollars...).
Any other noticeable difference between these two versions?