I get where ur coming from Kel - OP is free to ignore me, but I think it would be irresponsible not to point out that a cracking rig could be had for considerably less cash.
I completley agree with you on that point, you start to stray into the realms of diminishing returns at that price point.
As it is for gaming, what i think OP should do is drop the 590, the 2600k and the mega PSU for a 580, 2500k and an 850PSU shaving about £500 off his price that will murder any game especially his flight sim. Then when the next gen of GPUs are out sell his 580 and use the rest of the money (£650 / £700) to buy whatever new monster comes out on the new process.
Stagger the upgrade nicely