10 box machine setup, first timer help

[Ualaa]

I personally went with:

OS: Windows 7 Professional 64-Bit
Case: Antec Eleven Hundred Gamer
PSU: Corsair Modular, 1050 Watts
Motherboard: Asus Sabertooth X79
CPU: i7 3930K, 6 Cores/12 Threads
Cooler: Noctua NH-D14 (Air Cooler); will likely OC CPU to 4.5GHz.
Memory: 32GB, Corsair Vengeance 1600MHz, CL8, Low Profile
Video: eVGA GeForce GTX670 4GB, Superclocked
OS Drive: 2x OCZ Vertex 3, 120GB SSD, striped (in Raid 0).
Storage: 2x Seagate Barracuda 3TB
Optical: Asus 12x BD Writer

I've not actually 10-boxed yet.

The 3930 is the previous generation, but none of the current generation CPUs have more than 4 cores.
My plan is a Core + Logical Core per two game clients, with the first core/logical core for everything else; either that or have 5 Cores/5 Logical Cores, each on everything game related... or all cores/logical cores on everything... will see what is smoothest in mass PvP.
I typically have fifteen Firefox tabs, iTunes playing, and stream my play with XSplit Broadcaster, plus whatever Windows wants to do... while I play... sometimes have a windowed movie going, if I'm farming something or otherwise running repetitive/boring content.
I haven't overclocked the CPU yet, but 4.5GHz is a fairly modest overclock; will try 10-boxing without an OC first, if its smooth enough then I won't need to OC, but an OC (to 4.5GHz each time) on both my i5 2500K and i7 2600K was no issue and a significant boost.

Unless you're overclocking your Ram, I'd go for 1600MHz.
The 3930 doesn't support faster than 1600 base, but you can overclock; my motherboard supported up to 2133 I believe.
From what I read, 1600 CL8 is very comparable to 1866 CL10; price-wise they were the same... but I don't need to overclock the ram, to get equal performance.
I needed low-profile ram, with a maximum height of 22mm (or maybe it was 28mm), because of my cooler (which is one of the best Air based coolers).

I would recommend DX9 for 10-boxing, just because it will require quite a bit less video ram across 10 clients.
For five clients, you needed 1GB of video ram with DX9 and 1.5 GB of video ram with DX11; a rough guess is double that for 10-boxing.
My GTX670 4GB Superclocked actually ran 3 clients on DX11 and 2 clients on DX9 (I thought everyone was DX9, until I checked), everyone on Ultra settings and that never used more than 65% of the graphics card according to GPU-Z; on lower settings, I'm not using more than 30% of the card for five-boxing... so it should be fine for 10 boxing.
Aside from view distance (of players and objects, which I like to max), I'm personally quite content to play on low-medium settings on the slaves and medium settings on the main; the closer the settings are (between main and slaves) the faster IS Boxer can switch via Do Mapped Keys on a region swap (Window: Current > Do High Settings & Window: All without Current > Do Low Settings).

You don't need an SSD for the Operating System, but it is nice to have.
The gaming folder can go onto a cheaper SSD, and you'll notice a performance gain anytime textures (armor in particular) loads... whether in Org, a BG, or upon zoning or entering the world.