Here is an example of someone getting his i7 980X at 4.5GHz stable 24/7 with good temperature. And he is using normal watercooling only.
Is there any reason why you are not considering normal watercooling?
Perhaps you can build on his experience with your $400 budget.
Eg: (all Sidewinder prices)
CPU block: Apogee XT @ $70
Pump: Swiftech MCP 655 variable speed @ $78
Radiator: Feser Quad 480 @ $120 or Thermochill PA 120.4 @ $140
And say, the barbs, tubings, res and fans come together @ ~$110 (perhaps a little bit more)
And, if you can spend $650, then it is financially very comfortable.
Lastly, you must be very concerned about boot-up times? I see that you are planing to use 12 SSDs in Raid 0 setup? What is the expected bootup time for this array?
OVERCLOCKING is a crap shoot so to say u can get the best ram the best mobo and a high end cpu and u put it all together and as soon as u go 200+mhz all hell brakes loose cause ur cpu is not a good clocker cause ur not lucky but with a chiller if u keep ur cpu 5-10c below ambient even a crappy chip that dosent like to clock will take 800mhz like a champ
with direct die it will even do better
now lets say u have a chip that likes to be pushed well with a chiller u will do some nice clocks and with direct die u will make all ur friends cry cause u have the fastest rig around
now chiller for subzero are not practical cause u have to insulate ur tubing and ur pump and ur block and it just becomes a big hassle but u can run 10-15c below ambient and still condensation free and u can throw ur cpu gpu sb nb on the loop and have everything chilling
direct die will freez ur cpu and u have to insulate but all ur insulateing is the suction line and evap but ur limited to only cooling ur cpu but u can cool the hell out of it and get some insaine clocks