Yes you can.
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I could cool my OPC with WC prabally allot better then you cans can, and cheaper, I'd use one of my extra fish tank pumps(large one, 1000GPH) and i'd plug it in to the wall(obvoilsy) and have a 10 gallon tank.
then this is how i would set it up, buy a new 10 gallon tank for 10$, but it under the desk, have the pump in it,(its a internal pump, like i'd ever use a good external one oh a silly pc

) now i would make moldings of the video card and RAM and things like that(im thinknig clay, I dont think that would harm it) then make this plastic of the mold and have it split up to each part at the begging, have it run though the molds then i would have a 5 gollong long tank, that i would build of of plasitc and 100% silicone INSIDE the bottom of the tank, that it owuld drain into after, then i would drill a hole in the right of the case, and have a continius siphon back down into the 10gllon at the bottom.
the clay would be afew bucks, and the plastic owuld be 10$, and the 10 gallon tnak would also be 10$