[WoW] New computer for multiboxing

Hello! I'm currently running:

SEAGATE BARRACUDA 2TB 7200RPM SATA/600 64MB
PLEXTOR DVD±R/RW DL 24X SATA RETAIL BLACK
NZXT MIDITOWER H2 ATX BLACK
NZXT HALE 90 PSU 80+ GOLD 750W MODULAR
INTEL CORE I5 3570K 3.4GHZ 6MB S-1155 IVY
INTEL 330 SERIES 2.5" 120GB SSD SATA/600 MLC 25NM RESELLER
GIGABYTE GEFORCE GTX 670 OC 2GB PCI-E DVI/HDMI/DP
CORSAIR 16GB DDR3 VENGEANCE QUAD 1600MHZ CL9 (4X4GB)
ASUS P8Z77-V PRO Z77 S-1155 ATX IVY

Everything is stock(no overclock)
Using Win7 Ultimate.

While running 5 games I am having a issue with CPU(80% useage) and RAM (50+% useage).

This is obvious things that can be solved by overclocking the hardware, but then I will need to buy a better cooling system.

So I figured out that I'd rather want a better system, that might be able to handle 10boxing later:)

Upgrades I'm thinking about right now:

Case: Cooler Master Cosmos II Ultra Tower
CPU: Intel® Core i7-3930K Processor
Motherboard: ASUS P9X79 Deluxe, Socket-2011
RAM: Corsair Dominator Platinum DDR3 1866MHz
CPU Cooler: Corsair H100i Hydro Series CPU Kjøler

Further more, I plan on clocking the ram slightly, and clocking the CPU to about 4.5Ghz.

I noticed another thread like this, where it was asked a question that made me want to answer here:
I will be leveling up toons in 5/10 incredements.
I will be visiting large populated areas when I need to (/trade/AH/flight training/profession training) (This can however be done without logged into multiple characters^^)
Currently my plan is to do leveling(Quests, dungs, bgs), PvP(Random Bgs, 5v5 arena) And raiding is something i might try out later, but I do not want to be upgrading my system every time I want to go somewhere else:)

I was looking at AMDs 8core CPU at first, but left it behind for now.

When it comes to GPU, I will most likely be upgrading this later, unless my current is not good enough:)

I will happily read any feedback, but please stay constructive:)

TL;DL(?) What parts of hardware is mostly needed while multiboxing? Will the upgrade I set up affect anything noticeable? Other ways to increase performance?

Edit: Will my PSU be powerfull enough for the upgrade?

Case: Cooler Master Cosmos II Ultra Tower
This is fine

CPU: Intel® Core i7-3930K Processor
I run this with my 5 man and have done some 10 man with it, currently OC to 4.6 ghz with custom watercooling. I have had it up to 4.9, but I don't want to shorten the life of the cpu anymore then I have.

Motherboard: ASUS P9X79 Deluxe, Socket-2011
I have two computers and in one i use my EVGA which is cheaper edition EVGA X79 Classified works well for 5, but for my 10 I use my ASUS Rampage IV Extreme
http://www.newegg.com/Product/Product.a ... 6813131802 - asus rampage iv extreme
http://www.newegg.com/Product/Product.a ... Classified - Evga x79 classified

RAM: Corsair Dominator Platinum DDR3 1866MHz
I use G.SKILL Sniper Gaming Series 240-Pin DDR3 SDRAM DDR3 1866 on both my systems however evga is limited on RAM
http://www.newegg.com/Product/Product.a ... 6820231612

You will notice allot of ppl will fight over Corsair vs G Skill, but I have never had issues with G Skill so pretty faithful to the brand.

CPU Cooler: Corsair H100i Hydro Series CPU Kjøler
If you don't have the money to do a custom cooling loop then this should be fine, but I don't know if you will be able to OC to anything really high. No experience using it myself the H100, but I have seen ppl saying 4.1 ghz was pushing it with that. Guess it also depends on climate you live in etc. Right now it is winter in wyoming, so I could just open a window and the 10 degree weather could cool anything.

What PSU is strong enough?
I use this COOLER MASTER Silent Pro Gold Series RSC00-80GAD3-US 1200W ATX
http://www.newegg.com/Product/Product.a ... 6817171055

If you plan to use a sli or crossfire depending on what you are putting in you might need something bigger.

Your GPU will be one of your main concerns also besides ram, so make sure you select something good, I currently have a GTX 680 4GB on order for main and will be using a GTX 680 2GB in second while selling the old GTX 580 on amazon.