I don't understand why you would go with a 990x over a 2600k when you get equal, and often better, performance from the 2600k.
240GB SSD is unnecessary. You only need to boot from it and it does not increase performance during gaming. Actually gaming from one can ruin it... they aren't like hard drives and have a limited number of writes. If you are doing anything more than booting from it you are paying a LOT of money for something you are slowly destroying. If you are going to game from one don't get a 240GB one. Get one to boot from and another small one to game from to lessen your damage.
A 3TB hard drive is going to cause you grief. I would highly suggest getting 3 1TB if you really feel you need that kind of space. You should have multiple partitions anyway and this would open up stuff like RAID for video recording and not make you want to kill someone when you have to defrag a 3TB drive.
8GB of RAM is fine. 12GB only if you are going with an older chipset that supports triple channel or one of the new chipsets that are coming out soon.
Quad SLI needs over 1000w. Honestly you really need to get into 1200w at that point and that PSU needs to be good, high quality. Research it. I have a Corsair AX1200 and it is great... there are a few other high end power supply manufacturers as well.
Speaking of your graphics cards the GTX 580 is NVIDIA's flagship... not the 590. The 590 kind of sucks to be honest because it is simply 2 580 chips that are downclocked and put on the same board. It also only has 1.5GB of VRAM and if you want the best you need to pick up 4 GTX 580 3GB models. Keep in mind graphics cards get diminishing returns after 2 really so 3 is good but 4 is barely better. If you want 2 dual gpu cards as opposed to 4 single gpu cards then get an AMD 6990... They perform better than a GTX 590.
A dual gpu card will have a RAM amount on it that is something like 3GB for NVIDIA and 4GB for AMD. That means that each GPU on that board has access to half of it. SLI or Crossfire cards mirror each other so it is basically like having a single card as far as your computer is concerned.
If you want a good PC right now stick with a Z68 chipset 1155 socket. It is the current high end gaming chipset, overclocks easily, and runs cool. It is quad core but the 2600k performs on par with the 990x for a fraction of the price and actually outperforms it in a lot of games. Intel is also releasing a new chipset very soon that will be a new flagship CPU with 6 and possibly 8 cores.
Another thing about RAM... games are almost always 32 bit applications... actually I don't know of any that aren't... This means that they can only access 2GB of RAM. In some special cases they will have a switch that allows them to access up to about 3.5GB but NEVER more. They will pull the majority of that from your graphics card and just how much they pull depends on resolution and textures involved. Currently most games use less than 1.5GB but it is getting closer with new games due to the high res textures.
This basically means the only reason for having a sound card is for it to work as an amplifier for headsets or to push a surround system. It won't impact your performance in any way to use the onboard audio and some motherboards have amazing sound on their own at this point.
The only thing the PC you have drawn up there would excel at would be media editing large files and even then the difference would be minor over the 2600k.
When it comes to recording as long as the game is DX11 you will have ZERO impact by recording the file, but DX9 titles will hurt you quite a bit. Recording a DX9 title could very easily drop your FPS into the 30-40s. Rendering on my PC with a 2600k @ 4.3Ghz takes about 10 minutes for an average CoD clip with fairly heavy effects and less for one without hardly any effects added. I have never even come close to filling my RAM up and I am only using 8GB.
You just have to remember that it isn't about having the fastest computer(on paper) that money can buy so much as it is about having a faster computer than the average gamer because there is absolutely NO game designed for the enthusiast... only games designed with an enthusiast in mind.
Crysis 2 with the DX11 pack, Witcher 2 with Ubersampling, and Battlefield 3 with Ultra is the only thing really pushing computers right now and I can run them with my 2600k and SLI GTX580s without any issue. I actually noticed in the BF3 beta case that the 2500k and 2600k is outperforming the 990x. Building a computer is tricky because you waste your money if you buy too old or too high end and 1-2 years later you are obsolete again.
If you can wait Intel is going to release the 2011 socket and NVIDIA should be launching their 600 series early next year. That would get you superior performance than anything right now. If you can't wait you should stick to the 1155 socket because there will be more processors out that should perform better than the 990x for it and you definitely wouldn't be hurting with the current 2500k or 2600k processors. If money is no object I suggest 4 GTX 580s with 3GB so you can run high resolutions without it pulling from your system RAM.
These are all just suggestions though. If you want the 990x then, by all means... I just don't want you to buy it and realize you are getting outperformed by a quad core haha.
Also:
http://3dmark.com/3dm11/1179595
If you want 2 CPU:
http://www.evga.com/products/moreInfo.asp?pn=270-WS-W555-A2&family=Motherboard Family&series=All Motherboards&sw=5
You aren't going to get those kind of numbers from it like in the benchmark results and I can't guarantee high end performance in games but if you just want a big epeen that is how you get it. Make sure you have enough PCIe slots for what you are trying to put in it too. A case like the HAF X from Coolermaster should have plenty of room for you if you like it.
