By John A. Burek
(August 24, 2005)

Two parts water, one part coolant, and one part guts are all it takes to water-cool your PC. It may seem a little extreme for a garden-variety desktop, but if your CPU runs hot or you've overclocked parts of your system, nothing beats the cooling power of classic H₂O. Water conducts heat far better than air, and you don't have to be a turbogeek to perform the conversion. Modern kits make installation little more challenging than swapping a fan or a heat sink.

Water-cool your PC

Before you get started with this project, we recommend that you have the following:

Water-cool your PC

Water-cooling systems have three main parts: waterblock, pump, and radiator. The waterblock fastens onto your CPU or graphics processing unit (GPU), and cooling liquid circulates through its hollow interior to draw heat from the chip. The pump, either a discrete unit or part of the radiator or CPU-waterblock assembly, keeps the coolant moving. Finally, coolant flows through the radiator, which is cooled either actively (by fan) or passively (by sheer surface area). The principle's much the same as cooling a car engine. Hoses and fittings complete the hardware.

Water-cooling gear is sold in kits or as individual parts. We recommend kits for first-timers. Also, the system can be either fully internal or partly internal/ partly external. Internal systems are neater, but all the gear can overwhelm a case, blocking drive bays or slots. Internal/external systems overcome this problem by letting you place the radiator and perhaps the pump on your desk.

We opted for the latter and went with Zalman's Reserator 1 Plus, a premium rig that integrates pump, radiator, and fluid reservoir in a mammoth, passively cooled "Reserator" tower. The tower is big and expensive and could be mistaken for Darth Vader's air ionizer, but all the kit components are beautifully machined, and installation is easy. The system works with Pentium 4 Socket 478 or 775 PCs and most recent AMD-based PCs (Socket 462, 754, 939, or 940).

The pump moves coolant from the Reserator, through a hose that passes through a PCI-slot bracket, into the CPU waterblock, where it cools the processor. Another hose takes it to a second waterblock, where it cools the GPU. Finally, the liquid follows a third hose back out to the Reserator tower, where heat is dissipated through the tower's heavy aluminum fins.

Water-cool your PC

To begin, gather the required tools. You'll need screwdrivers (Phillips and regular), needle-nose pliers, a sharp knife, cotton swabs, and alcohol.

Unplug your PC, remove the power cord and the cover, and rest the case flat. Locate the CPU's fan/heat-sink assembly and disconnect its power cable from the motherboard. You'll next remove the whole assembly, but before you do, examine the clips or brackets holding it in place. Every CPU-cooler assembly is a little different; removing it may require springing a lever or releasing a clip or two with a screwdriver. Once it's off, remove all thermal-paste residue from the CPU using the cotton swabs and rubbing alcohol.

Next, check the CPU's socket type, usually emblazoned on the socket. (Ours was a Socket 939 Athlon 64.) Sort out the mounting gear, brackets, and screws you'll need for your socket. Depending on the socket type, you may need to remove the CPU-heat-sink mount from the motherboard (for us, a simple matter of two screws), and maybe the motherboard itself, to install a backing plate or insert screws from below. After removing the mount, we simply screwed two metal pillars from the kit into the empty mounting holes on the motherboard.

Next, apply an even layer of thermal paste from the kit onto the CPU. (A playing card spreads it well, as does a finger in a plastic bag. Just don't use your bare finger; skin oils could fry a CPU.) Place the CPU waterblock, centered, onto the CPU. With our Socket 939 CPU, we placed a bracket onto the waterblock and screwed it to the two pillars, turning each screw alternately until they were tight.

Use caution when removing the original heat-sink assembly. Some have sharp edges.

Water-cool your PC

Zalman's kit includes a GPU waterblock that works with most recent graphics cards. Start by removing the card from the PC. (Detach your monitor, unscrew the card from the backplane, and unplug any power connector.) If the card has a fan, remove it by pinching its spring-mounting pins from below. Again, wipe off any thermal paste.

Zalman provides two threaded GPU-waterblock-mounting pillars. Install these using their included screws and washers, inserting the screws from the card's underside, through the fan-mounting holes.

Spread new thermal paste over the GPU as before, then lower the GPU waterblock onto the GPU with the hose outlets pointing toward the card's top edge. Place its mounting bracket across the top and screw it into the mounting pillars. (The bracket fits a groove on the waterblock.) Attach with two screws, tightening alternately. Once compressed, the waterblock shouldn't wiggle.

Before reinstalling the card, affix the provided adhesive-backed aluminum RAM heat sinks onto the card's RAM chips for added cooling. After you reinstall the card, remove the cover from a PCI slot and replace it with Zalman's cover, which has two holes to let tubing pass into the case.

Save your old fan and CPU-cooler parts. You may need them if your water cooler ever fails.

Water-cool your PC

The kit provides a coil of silicone tubing you custom-cut. If you're using the graphics-card cooler, you'll need three lengths: one from the Reserator's outlet port to the CPU waterblock's inlet, one from the CPU waterblock's outlet to the GPU waterblock's inlet, and one from the GPU waterblock's outlet to the Reserator's inlet.

Measure carefully before cutting. You'll need to allow for extra tubing to avoid kinks and to place the Reserator conveniently. Cut the ends clean and square and attach them to the inlets one by one, triple-checking the connections and direction of flow. Before making each connection, slide the appropriate compression-fitting cap or tube clamp onto the hose. Then, work the tubing firmly onto its fitting. The CPU waterblock uses threaded compression fittings; screw the cap over the hose and fitting until snug. The GPU-waterblock connections use simple tube clamps; squeeze the clamp with pliers, slide it over the fitting joint, and release to secure it. The hoses entering and exiting the Reserator use snap-in "quick couplings" with valves that don't leak when detached. Fasten them to the hose ends with tube clamps.

Finally, somewhere outside the case, you'll need to sever the hose running between the Reserator's outlet and the CPU-waterblock's inlet to insert a flow indicator. This glass capsule shows whether coolant is flowing. Orient it correctly; the orange float inside needs to wiggle downstream. Attach the severed hose ends to the indicator using its compression fittings.

The Reserator must be level with or higher than your PC to avoid straining the motorized pump.

Water-cool your PC

Unscrew the cap on top of the Reserator and pour in the provided bottle of concentrated coolant, mixed with two liters of distilled water. Unlike tap water, distilled water is free of mineral deposits and prevents algae or other growths.

Now, switch on the Reserator and check the flow capsule--its float should jiggle in the coolant stream. If so, check all hose-connection points for moisture. If you see even a tiny drop, stop the pump immediately, tighten the fitting, and retest. If everything's dry after an hour's run, boot the PC. Monitor the CPU temperature by rebooting to the BIOS or checking a case-mounted or third-party temperature gauge. You should see a significant improvement. Now that's cool.