So as I am somewhat experienced with my AMD PC, I 100% agree with
@lionel
1.AMD is cheaper and if you're going for 500£ build that's the only choice
2.You might want to spend more on a CPU ,I own a Fx 6300 and i'm overclocking it to 4,4 GHz on my potato motherboard(risk of fire but fuck that shit xaxaxa)with AMD cpu for good performance you have to play around alot with settings ingame and offgame,but i'm getting anything from 30s in Kavala to 50s around the island on full server.(Fx 6300 is a very good cpu for it's price and performance)
3.Get yourself a R9 380 it's pretty much same price and kicks 960s ass in pretty much every case.(It won't influence your Arma 3 experience at all,but i doubt Arma 3 is the only game you'll be playing on this PC for next 3 or 4 years).
4.Don't listen to theese silly capitalists,good 7200 RPM HDD for start is fine,when i'm bored i'm just wiping mine off all files,after that it is fast enough to launch Windows 10 in about 30 seconds and it can run Arma 3 without textures popping (Seagate <3).Overall SSDs are only an optional upgrade to a base HDD imo,(slav engineering,best engineering cost wise xaxaxax),it would only speed up your launch time and make Arma 3 a bit more stable,(less FPS drops while going into towns or lot of shit happening ).It won't increase your FPS,just make it more fluent.
5.8 GB of ram is the best you'd go for 500£ ,you won't need 16 GB in a long time,and if you'd buy a 4 Ram slot motherboard,getting yourself another 8 eventually shouldn't be a problem in the slightest,even though 16 GB is overkill for TODAY gaming.
Link to my 1 year old thread (the room changed xaxa,no longer ugly)
And a bonus photo of how my stronk rig looks, it's worrth about 500£ after coversion from PLN