For a system with a CPU and 2 GFX, there is no reason from a thermal perspective to go to multiple loops. Two things to remember
1. Your 780 / Ti GPU or 2 of them will produce up to 300 watts each.... more if a 290x
2. A 4770k will produce a max of 140 watts at 4.6 Ghz
Despite the above.... your CPU will wind up running about 75C and the GPU at about 40C.
The most typical set up is:
Reservoir >>> Pump >>>Radiator(1) >>>GPUs>>> Radiator(2)>>> CPU >>> Reservoir
With 2 way SLI, Parallel flow to the 2 rads is recommended for 3 reasons:
1. GPU blocks are huge compared to CPU blocks and function effectively at much lower flows
2. At half the flow, flow restriction is just 28% of full flow.....so your flow restriction comparison for two in series is 2X versus 0.28x in parallel....a factor approaching 8:1
3. Parallel allows for both cards to work at indentical TDP and temps.
Figure 150 watts of calculated load for each 140mm of rad @ 1200 rpm fan speed
Figure 110 watts of calculated load for each 120mm of rad @ 1200 rpm fan speed
Let's assume that your plan is to start out with 1 780 (295 watts) and 1 4770k (135) ... for argument's sake, let's include MoBo (20) cooling as in the Maximus VI Formula, 1 pump (20 watts) and the assumption that at some point, ya will add a 2nd card in SLI.
So 470 watts w/ 1 card and 765 w/ two.....so using the above rule of thumb, ya need 3.13 x 140mm for one card and 5.1 for two cards
Radiators (assumption that 60% of theoretical max heat load handled by rads for Delta T of 10C):
470 x 60% = 282 watts
An Alphacool 420-45 will give ya 250 watts in push or pull and 302 watts in push / pull.
765 x 60% = 459 watts
An Alphacool 280-60 will give ya 170 watts in push or pull and 206 watts in push / pull or, in total, 420 watts in push or pull and 508 watts in push / pull.
Alphacool rules the roost in rads, other manufacturers will have slightly less numbers.
Blocks
-Best WB for the CPU on LGA2011 is Koolance 380i, best on Sandy Bridge, Ivy Bridge and Haswell is EK Supremacy.
-Best WBs are EK full cover.
Pump
I'd use any variant of the D5 for single card + CPU, at 2, I'd think about a 35x .... personally I chose a 35x2 double pump for 2 reasons ...1) if one pump breaks my system isn't down for 3 weeks waiting for replacement and 2) I can run it at half speed to cut sound.
Reservoir
Reservoir volume serves as a thermal buffer ..... more volume means that varying thermal loads have lesser effect on CPU temps as it takes longer for the larger amount of water to change temps....this means ya fans (usually controlled by CPU temps) will be more resistant to fluctuations in speed and therefore fan noise. I recommend decoupling the pump from res and all else in the system to cut down on vibration / noise. Bay reservoirs are prone to rattling and some report seam (glue) failures.
If it helps .... here's what I did:
-Phanteks Enthoo Primo Chassis
-Maximus VI Formula w/ built in WB
-4770K w/ EK Supremacy Clean CSQ) [3830046990808]
http://www.frozencpu.com/products/19628/ex-blc-1442/EK_Supremacy_Universal_CPU_Liquid_Cooling_Block_-_Clean_Plexi_EK-Supremacy_Clean_CSQ.html?tl=g57c603s1912
-2 x Asus 780 DCII w/ EK Liquid Cooling Block (EK-FC780 GTX DCII – Nickel)
http://www.frozencpu.com/products/21270/ex-blc-1529/EK_ASUS_GeForce_780_GTX_DCII_VGA_Liquid_Cooling_Block_-_Nickel_EK-FC780_GTX_DCII_-_Nickel.html?tl=c613s1928b133
-EK ASUS GeForce 780 GTX DCII Backplate (EK-FC780 GTX DCII Backplate - Black)
http://www.frozencpu.com/products/21273/ex-blc-1532/EK_ASUS_GeForce_780_GTX_DCII_VGA_Liquid_Cooling_RAM_Backplate_-_Black_CSQ_EK-FC780_GTX_DCII_Backplate_-_Black.html?tl=c613s1928b133
-EK-MultiOption RES X3 250 - White Acetal w/ Multiport Top and Fill Tube
http://www.frozencpu.com/products/21672/ex-res-677/EK-MultiOption_RES_X3_250_-_Liquid_Cooling_Reservoir_-_White_Acetal_6_Total_Ports.html?tl=g57c615s1940#blank
http://www.frozencpu.com/products/18485/ex-res-481/EK_X3_Reservoir_Multiport_Replacement_Top_-_White_EK-RES_X3_-_Multiport_TOP_WHITE.html?id=4NiLmkLB&mv_pc=1254
http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=59_1165_1162&products_id=36312
http://www.frozencpu.com/products/18760/scr-701/EK_G14_Thread_Fitting_Extender_-_Nickel_-_8mm_Fitting_Extender_G14_Ni.html?id=4NiLmkLB&mv_pc=1256
-Swiftech 35x2 w/ Heatsink and Noiseblocker Fan
http://www.frozencpu.com/products/14961/ex-pmp-173/Swiftech_Dual_Extreme_Duty_Small_Form_Factor_12_VDC_Industrial_PWM_Pump_-_Black_MCP35X2-BK.html
http://www.frozencpu.com/products/16233/ex-pmp-195/Swiftech_MCP35x2_Dual_Pump_Heatsink_MCP35X2-HS.html
http://www.frozencpu.com/products/image/16392/fan-1017_4.jpg/fan-1017/Noiseblocker_NB-BlackSilentPro_PC-P_80mm_x_15mm_Ultra_Silent_PWM_Fan_-_2500_RPM.html
Other items were 2 x Samsung 256 GB 840 Pro SSDs, 2 x Seagate 2 TB SSHDs, Six Eyes Fan Controller (Monitors temps only)....(5) extra Phanteks SP140 fans, Bitspower Temp sensors, flow sensors and fittings, 10/12 rigid acrylic tube.