They say one 120 Per Water Block so for 3 cards so a 360 radiator.
For more Info: http://koolance.com/how-to-build-a-water-cooled-pc
 $76.99  PMP-450 Pump, ID 13mm (1/2in)   SKU: PMP-450 (Not the S Pump)

$59.99 Radiator, 3x120mm 30-FPI Copper   SKU: HX-CU1020V
or
 $84.99 Radiator, 3x120mm Fans, 54mm Thick, 30-FPI Copper   SKU: HX-360XC When in Stock
 $9.99  Reservoir Top with Fill Port (60mm OD)   SKU: COV-TKTOP

$7.49 Reservoir Body, 60x50mm (WxL), 98ml   SKU: BDY-TK050
 
 $17.99 Reservoir Fitting Base (60mm OD)   SKU: COV-TKBTM
 
 $169.99 CTR-CD1224 12V or 24V Pump & Fan Controller With Display   SKU: CTR-CD1224
 $9.99 Coolant Temperature Sensor Plug, 10K Ohm   SKU: SEN-AP008G 2 or 3 Each
 

$19.99  INS-FM14 Coolant Flow Meter   SKU: INS-FM14
OR---------------------------OR---------------------------OR---------------------------OR---------------------------OR- The Cheep way
$79.99 CTR-SPD12X2 Dual 12V Pump Controller   SKU: CTR-SPD12X2 This is best because you can control your Fans
OR---------------------------OR---------------------------OR---------------------------OR---------------------------OR- The Cheapest way
$49.99 CTR-SPD1224M 12V or 24V Pump/Fan Controller   SKU: CTR-SPD1224M
 
 $14.99 Koolance LIQ-702 Liquid Coolant Bottle, High-Performance, 700mL (UV Blue)   SKU: LIQ-702BU-B

Liquid Coolants

Koolance's product warranty does not cover the use of 3rd-party coolants, coolant additives, or corrosion. Koolance LIQ-702 or LIQ-705 coolants are strongly recommended to help avoid issues with mixed metals or biological growth. Additionally, do not use aluminum with bare (unplated) copper or bare (unplated) brass in the same system. Do not use silver with nickel in the same system.
 
 $5.49 4-Fan Wiring Harness, 3-Pin   SKU: CBL-NX006P
$2.49 Fan Grill, 120mm   SKU: GRL-AP002P
LOWEST FANS
 $8.99 Fan, 120x25mm, 90CFM   SKU: FAN-12025MBK
 
LOW FANS
 $9.74  Fan, 120x25mm, 108CFM   SKU: FAN-12025HBK
$2.99 Radiator Mounting Screw & Nut, 25mm   SKU: BLT-HX025
 
HIGH FANS (Fan Grill, 120mm a Must)
$10.24 Fan, 120x38mm, 116CFM   SKU: FAN-12038HBK
Extreme Fans (Fan Grill, 120mm a Must) This one will take off a finger.
 $23.99 Fan, 120x38mm, 184CFM   SKU: FAN-12038HBK-184
 $2.99 Radiator Mounting Screw & Nut, 38mm   SKU: BLT-HX038
 
If needed:
$34.99 3x120mm Fan Radiator Shroud, Black   SKU: SHR-1020BK
 
Yes I use  http://koolance.com Parts for all my Water Cooling Needs.
No I do not work for them nor do I get any discounts from them.

I'm going to move this over to the Overclocking, Cooling, and Benchmarking section, as this is really just about the cooling aspect of these cards.  You'll get more responses over there, not to minimize bcavnaugh's great post up there, of course..

JohnWorfin
Next question, now that I was able to purchase them, will the  the EK parallel terminal block work to connect two hydro coppers?

NO, I ask them and they said the HC are custom built for EVGA and they did not want one made for the HC.

This is what I use on the HC.
Swiftech G¼ Male-Male Lok-Seal Short Extension Fitting (11-18mm Range) - Black
 

JohnWorfin
I want to run the cooling lines parallel through the cards. Does that mate with the EK block or do you use another?
 

Yes those will work for running the loop through the EK block in serial or parallel. You can also use Bitspower Crystal Link adapters if you want a different look. Either way works well. The crystal link setup looks like this
 

I pulled the trigger on the custom cooling loop, 2 radiators, pump-reservoir-controller-combo, compression fittings and tubes. Parallel GPU cooling and CPU cooling. It arrives next week. Wish me luck, this is the first PC build in over a decade