The components inside your PC generate heat. Your standard heat-sink-and-fan combo is usually sufficient for the average user, but when you push your components harder, they'll run hotter. If you want to overclock your PC to the bleeding edge, you'll want to build a liquid-cooling system for your PC to ensure that your precious components don't burn out.
What You Need
Following is a list of the equipment and parts we used for this setup. Part costs vary, but those we used totaled about $220.
Case: We set up our system in the Antec P180 Advanced Super Mid Tower. It's an older case, but sufficiently roomy. Pretty much any case will do, but keep your space constraints in mind--you'll need plenty of room for your components, your tubing, and your reservoir. The P180 sports a few 120mm fans--we'll be using the one on the rear.
Radiator: For this setup, we'll need a radiator. Warm liquid is pumped through the radiator while the fan pulls air through the radiator's grille, transfering heat and then expelling it from the case. We decided on a 120mm Black Ice GT Stealth radiator because it fits with the fan mounted to the top of our chassis. Be sure to pick a radiator that fits your particular case.
Cooling block: We're using an Intel Core i7-990X Extreme Edition processor, so we need a CPU cooling block that fits the 1366 socket. We found it in the Danger DEN MC-TDX. Choose the CPU block that's right for you, but remember not to mix metals, or you could risk galvanic corrosion. In a nutshell, mixed metals in an electrolyte (in our case, water) swap ions a bit more readily than parts of one metal. This causes the metals to break down. All our components are made of brass.
Pump: The pump is responsible for circulating the liquid through the chassis. We're cooling only the CPU, so we don't need anything too impressive: we went with the Danger Den DD-CPX1, a smaller, fairly inexpensive unit.
Reservoir: The reservoir holds all of the liquid used for cooling, as well as providing a spot to quickly check on how the liquid levels are doing. We're using the XSPC 5.25-inch Bay Reservoir. Bay Reservoirs fit into the same slot as a DVD-burner, which makes them very convenient--no need to pry off our case walls just to check the liquid levels. And our chassis has plenty of 5.25-inch bays to spare.
Barb fittings: Barbs--as these fittings are called--attach to the various components, and tubing attaches to the barbs. The barbs are available in a variety of sizes. Larger barbs will allow for larger tubing, which improves the flow of liquid, but requires a bit more space in the case. We'll go with barbs with an outer diameter of 1/2 inch.
Tubing: A dizzying number of options exist when it comes to tubing, but we want to economize. Tubing size is tied to the barb size--generally. For 1/2-inch barbs, you'll generally want 1/2-inch tubing. We're going to use slightly smaller 7/16-inch tubing, however. It will take a bit of extra muscle and care, but the smaller tubing is flexible, inexpensive, and wraps tightly around the 1/2-inch barbs to form a perfect seal.
Clamps: If you'd prefer to use the larger, 1/2-inch tubing or a different size altogether, you'll need clamps to ensure that your tubes are held in place. These are inexpensive--just get the size that matches your tubing and barbs.
Liquid: The liquid makes up the bloodstream of the liquid-cooled PC's circulatory system. There are a variety of options, but we're sticking to the simplest, and the cheapest: distilled water. Be sure you're using that, and nothing else--tap water is full of impurities that could potentially cause algae and the like to grow in your system, clogging tubes and corroding the water blocks.
Putting the Pieces Together
Now it's time to start laying out your liquid cooling system. Planning is key, so sketch a diagram--something like the one below--before you start the assembly process.
The water will be at its coolest point once it leaves the radiator, so we want it to pass over the CPU right away. The warm water that's transferred away from the CPU will then be routed back into the reservoir. From there it heads through the pump, and back through the radiator, completing the cycle.
Now, it's time to get our feet wet.
First, attach the reservoir, radiator, pump, and motherboard into the empty case. (Mounting screws came with our parts.) Mount the reservoir into a free 5.25-inch drive bay, and position the radiator to straddle the 120mm fan on the roof of the case. The pump is small, but lacks mounting screws, so we're using some Velcro tape to keep it snug and secure at the base of our 5.25-inch drive bays.
Next, attach the tubing to the CPU water block before you mount it onto the motherboard. The 7/16-inch tubing we chose for our 1/2-inch barbs is going to prove its worth here. Once you've attached the 1/2-inch barbs to the block, you'll need to slide the tubing onto the protruding ends. It'll take a fair bit of effort, but you'll be hard-pressed to find a tighter seal. If you can't quite get the tubing around the barb, try heating the end with a blow dryer. Once you have a tight seal around the barbs on your CPU block, mount the block onto your motherboard.
The next step is to get that tubing connected to our pump. Attach a pair of barbs to the inlet and outlet ends of the pump--the pump's manual and our photos should show you which end is which.
Next, guide the tubing from the CPU water block down to the pump, taking care to bend the tubing as little as possible. Once you've gauged an appropriate length that leaves a fair bit of flexing room, use a sharp blade to cut the tubing, and then attach it to one end of the pump. We'll repeat this step to connect the pump to the reservoir, the reservoir to the radiator, and then back to the CPU.
Now for the most important part: leak testing. (We may be liquid cooling, but we don't want to soak our equipment.) Now that everything is mounted into the case and the tubing is attached firmly, we'll jump-start our power supply to give our liquid-cooling loop a "dry" run.
Grab the power supply, and look at the large 24- or 20-pin ATX connector. There are plenty of wires, but we're interested only in the solitary green one, and in one of the many black ones--it doesn't matter which. We're going to be closing the circuit, much like the motherboard switch would. But we're using a paper clip.
Fill your reservoir with distilled water; to prevent spillage, you may need to slide it outside of your case a bit or pour the water via a funnel.
Be sure that the only thing connected to the power supply is the pump. Bend your paper clip into a "U" shape, and slide one end into the green wire's connector, and the other into a black wire's connector.
Flip the power supply switch on, and it should hum to life, triggering the pump, which will begin circulating water. Once your reservoir is at the halfway point, shut the power supply off, and fill up the reservoir again--we're trying to eliminate any air bubbles that might creep up within the loop, to optimize circulation. Flip the power supply on again, and observe your machine. If water is circulating and your parts are still dry after running for a while, you're done.