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The pixel density for many 27 inch monitors at 1080p is atrocious. I'd rather get a 120Hz/144Hz monitor that's a smaller size.

Probably a BIOS problem. There may be an option to enable the port.

Most of your parts are well picked, but I have a few recommendations.
 
First of all, two GTX 670's won't always get you a constant 120FPS in-game, but 60FPS shouldn't be a problem.
 
16GB of RAM is excessive for almost everyone. For reference, most games can only utilize up to ~4GB since they're 32-bit applications.
 
The G600 is more suitable for MMOs, if that's fine with you. If you want a mouse better suited for shooters, I can vouch for the Razer Mamba 2012.
 
Other than that, it's a good build. Just keep in mind that a cyan case with red RAM and a black motherboard is a little bit of an odd color scheme, so you might like these RAM sticks: http://ncix.com/products/?sku=59431&vpn=CMZ8GX3M2A1600C9B&manufacture=Corsair&promoid=1280

A good mouse, keyboard and a fast monitor are very important. Also, be sure that you have at least 60 frames per second constantly, it'll help you out the most.

The Samsung SSDs are very reliable, and they offer a 120GB capacity. I highly recommend them.
 
Excellent value: http://ncix.com/products/?sku=77210&vpn=MZ-7TD120BW&manufacture=Samsung%20Memory%20%26%20Storage&promoid=1280
 

There seem to be some issues with Sony Vegas Pro and hyper threading, as described here: http://www.videoforums.co.uk/sony-vegas-media-studio/28851-warning-intel-core-i7-users.html
 
It seems like the 3570K would be the better choice. Good luck.

The 2GB TOP edition cards will be more than adequate until you reach triple screen setups.
 
I'm actually using one of them now, and I highly recommend it. Good luck.

Nice build, and that's one impressive camera

There are few instances where faster memory will benefit you noticeably. One of the rare examples is when using your RAM as a drive, and for some benchmarks.

You'll probably be interested in the 802.11ac solutions such as these: 
Router: http://ncix.com/products/?sku=74214&vpn=RT-AC66U&manufacture=ASUS&promoid=1280
 
PCI-E Adapter: http://ncix.com/products/?sku=77959&vpn=PCE-AC66&manufacture=ASUS
 
With the recent flagship phones such as the ASUS Padfone Infinity and the HTC One providing 802.11ac support, it's likely that we'll see an abundance of 802.11ac devices in the near future.

Also not true. If your card doesn't need the RAM, it won't affect frame rates whatsoever. It's when it runs out of RAM that it can drastically affect performance, much like when system RAM is depleted and the computer then accesses the page file, which is usually slower.

Not entirely true. They trade blows with each other but they're relatively equal.

I'm not sure if you can get a good mat for $20, but for $40 the Razer Scarab is incredible. It still hasn't shown any sign of deterioration after over a year of use.

As far as case fans go, you can go with just about anything as long as the aesthetics, noise, and price are acceptable. Check out the Bitfenix Spectre Pros or Noctua NF-A12/A14s, the former is cheaper and great looking while the latter is expensive but outperforms practically anything it competes with.

It sounds like a power saving issue. Change your GPU settings to "prefer maximum performance", and do the same for your CPU (probably under power settings in Windows). Good luck.

The 3930K is very comparable to the 3960X. It's great for video editing, but is overkill for most games.
 
As for the GPU, it really depends on what you play.

It's really only for looks. It has a negligible effect on cooling performance and since most are brushed aluminium, they're rather useless for any sort of protection other than from electricity.

I'd expect a frame rate of around 60 for the most part in Battlefield 3, with AA off (which you should do). If you're a serious gamer though, I'd stay away from any monitor that isn't 120Hz or more.

It really depends on what you're using it for. I'd choose the Corsair 900D for an X79 water cooled build, the Bitfenix Prodigy for a Mini-ITX build, and the Intel NUC or a tablet for portability.

Get a 23/24 inch 120Hz monitor if you're a serious gamer. 27 inches for a 1080p monitor is too large, the pixel density is atrocious.

I have the Mamba 2012 and find it to be a strange experience on a Scarab. I don't use it.

Check out my avatar, it's all in a Define R4. I LOVE Noctua's fans, there are 3 NF-A14's and 2 NF-F12's on the H100i.

The Spectre Pro's offer about 3-5 degrees difference from their Noctua counterparts, from what I've seen. They're probably exactly what you're looking for.

The Bitfenix Prodigy is probably the best choice of all of them. Tons of colors, mesh panel options and even a windowed side panel is available. Lots of radiator support for its size, as well.

I don't know if you can, but personally I don't like the look of them. Maybe you should consider using 90 degree fittings with clear tubing.