Drop the NB/SB/Mosfet blocks. You don't need them unless this build is simply about 'look at all the cool hoses'. They are pointless and will just restrict flow from the CPU and GPU's
Use 1/2"ID tubing; forget 3/8 for what you are trying to do.
DO NOT USE Thermaltake coolant...or any other pre-packaged 'pretty color' coolant. Use distilled water and some biocide or PTNuke from Petra's Tech shop. If you want colors, use colored tubing. The color in the coolant collects and forms goopy crap in your components.
I've never been a fan of the DD TDX block...I had one, hated it. Look into some better CPU blocks. I use a D-tek v2 on my Q6600, works excellent. There are a handful of good ones.
If you already have a 4x and two 2x rads, you don't really need any more than that... not unless you want to go with no fans lol. With reasonable fans like Scyth Kama 70CFM (40dBs?) that should already dissipate 700W or more (based on a 3x120 rad dissipating ~350W to 400W at that fan CFM)
Your NB is designed to run that hot. What we as humans find as 'hot' temperatures is different than what is designed for PC components. Yes, cooler is better, but you aren't going to gain anything by WC your NB or SB...except to say its cooler. When you WC your GPUs and CPUs, you can gain some significant overclocks and they will be more stable under loads with more voltage. Typicall, rule of thumb I follow is, if there is a fan/active cooling on your NB, you are fine.
From experience when i had my 780i, i Was using 3/4 with 240 koolance Rad, DangerDen Pump and Koolance block. I was forced to block the CPU, NB and Mosfet to get my Q9650 running at 4.1Ghz rock solid.
I don't recommend having your GPU on the same water loop because videocards run so much damn hotter. At the same time with the way, how fast videocards are replaced. I stopped waterblocking my videocards. but if you want to watercool the cards then just have a different loop with a different pump and rad, Figure 120 for each card, so if you have 2 cards then 1 240 rad will do fine.
also for the record, i have my 2600k @ 5.1Ghz @ 1.5v with 31c idle and 55c load with the same damn DangerDen Pump, Same Damn Koolance Rad and same Waterblock. Don't take corners and if you choose to go 1/2 just remember those tubes don't bend worth crap and All the blocks and rads will just reconvert your 1/2 back to 3/4 via tube barb nipple.