For $250 the best bang for your buck is going to be either an XSPC RASA kit or a Swiftech Edge (or Ultima) kit. You'll want the 220 rad version for just CPU.
Adding the GPUs to the loop will cost a fair bit more as you'll need GPU blocks and at least another 320 or 420 worth of rad space.
I don't think to add the GPU blocks because I think the stock MSI cooler is pretty awesome..
.. I just wanna use the liquid cooler for the CPU or maybe motherboard..but for motherboard, it kinda hard and risk since we need to uninstall the stock cooling systems..Does the Swiftech Edge Kit got both cpu and gpu block?