1.a As always.... defining best requires parameters..... Best cooling, at least at the time of my last full loop build was Alphacool. What other parameters are you interested in ? Alphacool rads also have 7 ports (some competitors have just 2) and screw protectors (whiuch stop you from accidentally puncturing your rads when attaching fans) are issues i would consider important. The issue with Alphacoolk rads is that the residue left after manufacturing can interact with some engineered coolants. Mahems products for example often do not react well with this residue. All radiators should be thoroughly cleaned with both an acid and base solution before use. You can look at martinsliquidlab site for detailed test data and reviews.
https://martinsliquidlab.wordpress.com/
You can find all of martins data tabulated in spreadsheets, along with sizing instructions, here:
http://www.overclock.net/t/1457426/radiator-size-estimator
1.b Today's rads are low fpi (fins per inch) so the old adage of getting high SP fans is no longer applicable. Phanteks are the best radiator fans on the market at present ... and fortunately, they give you a nice set of them in each of their cases. Their cases also come with a fan PCB which provides PWM control of 3 pin DCV fans... essentially a "best of both worlds" scenario..... lower cost and no low speed hum / clicking typically associated with fan motors at low speed. Here's the Phanteks beating the Noctuas by 3C while spinning 300 rpm slower
http://www.overclockersclub.com/reviews/phenteks_f140/3.htm
Here's silentpcreview's rankings (Phanteks 1st place)
http://www.silentpcreview.com/article1345-page7.html
2. Usually, to answer this question, I'd have to ask what CPU as the best block would historically be different fro a 1150 CPU versus an LGA 2011 for example. At this time however, the EK Supremacy Evo beats all comers in every category.
http://www.overclock.net/t/1505481/summer-water-block-round-up-2014
3. As for pumps, a D5 is basically a D5.... I always bought the custom modded ones from frozencpu but alas they are no longer active in the marketplace. I use the 35x2 double DDC pump ... If I have to choose a D5, I'd take the Swiftech adjustable speed pump. I would recommend against a pump / reservoir combo as pump vibration is transferred to the res .... and all your other stuff if using hard tubing.
4. The Phanteks PCB is superb, simply the best fan control device on the market. I am using 3 of them in my Primo to control 3 sets of fans independently. Swiftech and ModMyToys have long made PWM PCB devices....ModMyToys has long made DCV controlled PCBs ... Phanteks however is unique in that it can be used while being fed from a PWM or DCV header.
Channel 1
CPU Header => Pump No. 1
CPU_OPT Header => Pump No. 2
Channel 2
CHA_1 Header => Phanteks PCB => (6) radiator fans on 420 radiator
Channel 3
CHA_2 Header => Phanteks PCB => (4) radiator fans on 280 radiator
Channel 4
CHA_3 Header => Phanteks PCB => (6) case fans
Speed control is via the MoBos Windows based fan control utility which gives you 5 points to set up a fan curve for each of the 4 channels.
5. Bitspower is considered the "top of the line" but as was said above, you can easily spend $500 - 1000 on fittings
6. Hard or flexible tubing..... I prefer rigid acrylic tube.
7.a I'd suggest one of these:
AC to DC Adapter - 110V AC to 12V DC Converter w/ Standard 4 Pin (5000mA Max)
http://www.frozencpu.com/products/9106/bus-192/AC_to_DC_Adapter_-_110V_AC_to_12V_DC_Converter_w_Standard_4_Pin_5000mA_Max.html
Again w/ FCPU down, you can also find them on Amazon for about $14 .... it allows you to start the pump and fill / bleed / leak test the loop without putting any power to your system thereby not putting any of your components at risk.
7.b A fill tube for your reservoir might be in order..... I prefer a top fill / bottom draw arrangement and to do this you will need a 3 port replacement top
7.c EK GPU water blocks may not take 1st place for GPU cooling, losing tot he competition by 1-2C, but they destroy the competition in VRM and Memory cooling, leading by as much as 30C and 12C in VRM and memory cooling.
Here's our last Enthoo Primo build:
Alphacool XT45-420 on top
Alphacool XT60-280 on bottom
Swifttech 35X2 Pump
EK Res3-250
EK Full Cover GPU Water Blocks w/ backplate w/ Gelid Extreme YIM
EK Supremacy CPU Water Block w/ Shin Etsu 751 TIM
Phanteks F-140SP fans (16) ... pic was taken before pull fans installed.
Phanteks Fan Control PCBs (3)
Asus MoBo Water Block
Case fans shut off when temps are such that fan curve would be below 350 rpm and have 15 second ramp up and ramp down times.
Radiator fans operate between 325 and 850 rpm.... with 5 second ramp up and 45 second ramp down times.
When designing the loop:
a) Make sure to include a drain port, fill port and bleed ports. The drain you can see in the pic under the bottom rad, right side (quick disconnect). The fill port is accessed thru the top grille of the case. By positioning the rad a bit forward, you are able to have the top radiator ports accessible. A 40mm extension screwed into the rad makes this easy. There are two bleed ports, one next to the fill port and the other on top of the reservoir.
b) Provide some vibration isolation for the pump bu using a short section of flexible tube if usinga crylic rigid tubing for rest of build.
c) Your GFX cards must be 10.6" or shorter to use the included reservoir mount.