Haven't followed the specs much, but here are some general insights:
1. NEVER SKIMP OUT ON THE POWER SUPPLY. Get a true-rated PSU. Wattage depends on the chosen specs but usually the higher the better. This is THE MOST IMPORTANT PIECE in your system, because it's the one literally powering everything hence, the name, OBVIOUSLY... I'm being redundant... Anyway, make sure that the one you pick has: Enough wattage to power everything you have: The Motherboard, GPU, Hard Disk(s) and any accessories you might fancy, like intake and exhaust fans. Also make sure that all the power connectors you will need are there.
2. Pick a good case with a lot of room for good ventilation and wire management. Heat has a tendency to do bad things to good computer parts.
Now, I know you mentioned that those two aren't needed, but just in case the dimensions of the new parts you pick or their power consumption will not be enough for your current PSU, you will need to buy new ones of those as well. Just putting it out there.
As for your budget, you can probably get a Titan (or something equivalent) and still have at least $1500 remaining. That's a lot of money you can then use for the other parts. Even then you can probably splurge on those new-fangled 4K/G-Sync monitors (G-Sync if you use Nvidia GPUs) and have some more extras.
