CPU: Intel Core i7-4771
RAM: Kingston KHX1600C9D3/4GX *4
GPU1: Powercolor Radeon 7950
HDD1: Samsung 840 256GB
HDD2: Crucial BX100 500GB
PSU: Corsair 450HX (modular)
Case: Coolermaster Centurion 5 II
Sound: Asus Xonar DGX
Monitors: Dell U2312HM *3
Operating System Debian 64-bit + Windows 7 64-bit + Xen 4.1
Others: Aten CS1794 4-port HDMI+USB KVM
So here's the kicker: This is my AAA gaming machine, whos BIOS/EFI never booted Windows (I'm also excluding grub loading Windows). My usage scenario: Linux is always booted with Intel's IGP and MB's onboard sound. Then I start my Windows virtual machine which controls the Radeon and Xonar. Adding some USB stuff, and my virtual machine works great. The setup was specifically chosen for Intel's VT-d support.
In case you are wondering, I do play AAA games, like Deus Ex HR (which was the 1st in a virtual machine, but with my previous Z68/i5-2500 setup), Skyrim (whos 200+ Steam hours never saw native Windows), Project CARS, iRacing, last 2 Wolfensteins (I'm playing Old Blood this week).
Actually, yesterday I even did a tech support, by pausing the game (W:Old Blood), switching to the linux KVM port (CS1794's 1st and 2nd port are connected to this PC), do a TeamViewer session, finish, return to the game.
PS: while the CPU+MB are still relevant, I am keeping my out for next-get GPUs.
PS2: there are a lot of issues with VT-d in consumer HW, the biggest ones would be sound (I tried maybe 7 cards) and USB (around 4 controllers). On sound, Xonar DGX and Hercules Fortissimo IV are the best (PCIe and PCI respectively), followed by onboard audio. On USB front, Intel's HW is unbeatable (considering the same chip is rebranded for workstation target). 2nd was a VIA USB3 controller, but I've had issues with my FFB wheel (like not taking the input for around 1s on many ocasions...a racing no-no).