In your case I would suggest getting more cash and moving to new set up...
I m not sure about that psu age and if it supports new sleep modes for intel cpus, but case can be reused...
There are few ways to save cash and 1 option is to go haswell and you can save on ram... but with 250$ you can get i5 and motherboard and stick old ram in and if psu can be used for haswell it awesome...
Otherway you could go for skylake or wait out new kabylake or zen...
As a gamer get 4 core good cpu...
Latter you can get yourself gpu... moddrn cpus have pretty good inbuilt gpus...
Anyways latter I would suggest buying 250gb ssd and psu might be a good investment
After that gpu and ram to 16gbs