Ask the Doctor: Feelin' My Flow


After many years of heating my room with an air-cooled PC, I’m thinking about building a water-cooled system. Since most rigs have blocks for just a CPU and maybe two videocards, I need some advice on how much pressure the pump needs to put out. My liquid circuit will include blocks for a Phenom 9950, two videocards, and some OCZ Flex IIs (liquid-cooled RAM). I’m worried about flow restriction from the length of the liquid circuit and the cooling effectiveness for the RAM.

—Michael O.

The Doctor fired up Dream Machine 08 to answer your question, Michael. And he’s pleased to report that he saw no difference in cooling prowess whether the machine’s Laing D5 variable-speed pump was cranked to its highest (317 gallons per hour) or lowest setting. It appears that the actual speed of the coolant through the looped system has little effect on its temperatures.

That said, the Dream Machine uses half-inch tubing for its cooling loop, which provides better cooling performance than three-eighths-inch tubing. Keep your tubing and connectors a uniform size throughout your system to ensure maximum performance. And be mindful of how you wrap your tubing around your system. Cooling performance decreases if your tubing is kinked or restricted in any fashion (for example, using an L-shaped pipe to style your setup around a corner or bend). However, as long as the pump is able to move coolant through the system, your water-cooling setup should be fine.

SUBMIT YOUR QUESTION Are flames shooting out of the back of your rig? First, grab a fire extinguisher and douse the flames. Once the pyrotechnic display has fizzled, email the doctor at for advice on how to solve your technological woes.

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