First remark, there is no i7 @ 4.0 GHz. That is only achievable with heavy overclocking.
Have a look at these guides:
In general, I would not look at a Quadro card. Their price/performance is severely lacking. Also forget about a Highpoint Rocket. It is - sorry to be so blunt - only a second rate controller. I would seriously consider to use the savings on the video card for extra storage or a better raid controller.
I think that a single i7-920, overclocked to 3.6 GHz and properly tuned can outperform a dual 5520 system rather easily. In the PassMark benchmark my system, outlined in the PC Buying Guide, easily outperforms a dual W5580 with double my memory and that uses a Quadro FX5800 video card.
Thanks for the response, I will have to read your guide twice so I can digest all of it. The quote I received from Boxx lists the Intel 17 Quad core
Enhanced Performance Processor as 4.0Ghz. Why would they list it as 4.0?
I can only assume they overclock their system to 4.0 GHz as standard. It makes it appealing and may be a good marketing trick. However the fastest i7 is the i7-Extreme 975, which runs at a standard clock speed of 3.33 GHz and costs around 890 Euros over here. Probably Boxx uses that to increase their price, because you get such good performance.
If you choose an i7-920, which has a standard clock speed of 2.66 GHz the cost is currently 230 Euros here. I have had no trouble overclocking the i7-920, even to extreme values like 4.2 GHz.
Boxx delivers good stable and reliable systems, but you pay dearly for that.
The Intel i7 comes in three flavours the 920 @ 2.66ghz, the 940 @ 2.93ghz, and the "Extreme" 965 @ 3.2ghz. It very much sounds like you have been using "overclocking" specifications. But beware overclocking - it brings with it all the other issues of heat management and performance v. longevity.
You correctly mention the clock speeds of the 920, 940 and 965, but there is also the 975, which runs at 3.33 GHz standard.
As to your remark about overclocking, you are absolutely right, the cooling is essential. You can almost feel the temperatures in your case go up with every .1 GHz of extra clock speed. Higher temperatures mean less longevity and higher energy bills, because the components all use extra juice when overclocked. But in a controlled environment where you have temperatures low enough to give stability in a good case/chassis there is nothing wrong with overclocking, as long as you know what to watch for and your memory can handle it.
Temperature and energy considerations are the reason I only run my system at 3.6 GHz, until I need the extra speed. Then I go up to 4.0 GHz for short durations, while monitoring the temperatures. I shuttle back when I get worried, but this has never happened yet (and I take large safety margins into consideration). Even running Prime95, which is extremely taxing on the CPU, I have not yet gotten a CPU temperature over 62 degrees C, far below the Intel specs for this CPU.