Keeping Hot Systems Totally Cool

System builders can serve this market by creating computers that feature exotic cooling systems for maximum gaming performance. One of the best ways to achieve that is by deploying thermoelectric coolers (TECs), which are becoming more readily available as their popularity increases. TECs work even better when supplemented by water-cooling systems; I'll show you how to combine these two high-powered cooling systems.

Demand for PC-cooling systems should be intense. IDC predicts that 90 million 'gaming ready' PCs will be in homes by year's end . They'll all need high-end cooling systems.

In this recipe, I will show you the basics of installing a thermoelectric cooling system for any high-performance PC, regardless of its intended application. Best of all, you'll be able to purchase all the necessary components for less than $650.

ALL ABOUT TECS

To get started, let's take a quick look the mechanics of TECs. Then we'll move on to the how-to's of actually building out such a system using TECs supplemented by traditional water-cooling.

A TEC is a wafer-sized module; think two small, flat, square pieces of metal. It has two protruding wires: one plugs into the conductor on the TEC unit, and the other plugs into the system's power supply. For this Recipe, the TEC will lie on top of the CPU chip. Here's a photo of a typical TEC:

Thermoelectric cooling has been around for a long time, at least conceptually. The principle was discovered in 1834 by scientist Jean Peltier; today it's known as the Peltier Effect. The basic is to pass electricity through a pair of dissimilar metal semiconductors. This creates heat at one end of the junction, which, in turn, causes heat to flow from the other end of the junction. If you carry away the heat from the "hot side" of the TEC, this perpetuates the flow, effectively creating a solid-state, active heat pump. More recently, engineers discovered that this effect is a great way to cool microchips inside a computer.

Because TECs have no moving parts, they are very quiet and highly reliable. TECs also can move a lot of heat. This makes them more effective than either conventional forced-air convection cooled systems or typical water-cooled systems. In fact, TECs can bring a computer to below ambient temperature. In other words, the computer can be made cooler than the room it's in. That's something no air-cooling can do alone.

But effective as TECs are, they do have drawbacks. First, TECs need a great deal of electricity to create the Peltier Effect. Second, they actually generate some heat due to inefficiencies and losses.

This is why I recommend adding a water-cooling system: to draw excess heat from the TEC. However, if the cooling system fails, you could have disastrous effects. The TEC will rapidly build up a great deal of heat.

Finally, anytime you cool a thermodynamic system below ambient temperature, you create the potential for condensation. In other words, as the air inside the case cools, water vapor in that air will form into water droplets. If these water droplets come in contact with the computer's electronic components, the components could be quickly ruined. Therefore, a system builder must carefully prepare the computer's internal components, creating strategically placed gaskets and seals that will block the water and keep the system components bone-dry. INGREDIENTS

Here's a list of the hardware you'll need for building a hot but cool PC.

Copper "Cold Plate": This is basically a solid piece of thin copper, sized to fit the CPU chip. It will be situated between the TEC and the CPU itself, to increase the efficiency of the heat-transfer process. For best results, have the copper plate "lapped" to a mirror-like finish by polishing it with fine-grain metal sandpaper. These plates are by online stores that cater to overclockers and the liquid-cooling market.

Thermal Grease: This fills in tiny gaps that naturally occur between the bonding points of the TEC and the copper plate. It also increases the thermal conductivity across the gap between these mated materials. I recommend Arctic Silver 5 High Density Thermal Compound. It contains real silver, a good conductor of heat.

Dielectric Grease: This protects the CPU socket from condensation formation once the system is up and running. Prior to installing the CPU chip into its socket, spread a little of this material into the holes to seal them. The dielectric grease conducts electricity, but does not permit water, allowing the chip to run while keeping it dry.

Neoprene Gasket Material: Neoprene is an ideal gasket material because it is chemically inert. This means it does not conduct electricity, and it is water-resistant. It's also a good insulator, meaning it helps keep the heat (and cold) where you want it. Neoprene is soft and flexible, so you can cut it with a utility knife or razor blade. You can buy it in sheets that can be cut as needed for proper fit.

TEC Unit: TEC units typically come with a pair of unterminated bare wires. These are often rated in watts, which refers to the maximum amount of heat they can remove from a thermodynamic system (Qmax). Other specs you'll want to look at are the maximum temperature change (Tmax), and voltage and current (Vmax and Imax, respectively). Check the TEC's dimensions to make sure it's the right size for your particular application. And make sure you use a "potted" TEC unit, to prevent condensation from forming inside the TEC itself.

Conformal Coating: This creates a coating over the motherboard that protects against condensation. While you can get this type of product in liquid form (applied with a brush), the aerosol type allows for a more even coating with less effort. A single 12-ounce container (either liquid or aerosol) should be more than enough for one computer system. I suggest you purchase both liquid and spray supplies—and I'll explain why later on in the recipe.

Swiftech (the maker of the power supply I discuss next), recommends this MG Chemicals product, Silicone Conformal Coating 422/422A, for conformal coating. You may want to get a small bottle of this liquid for applying in hard to reach areas, such as around the inside of your CPU socket(s). For this to work, you must get complete coverage. A light coating over the entire area is needed. While the coating loses its tackiness in about 30 minutes, ideally you should allow it to dry for two days before proceeding with your assembly.

Silicone Rubber Adhesive Sealant: This creates a watertight seal that won't conduct electricity. It resists a wide range of temperature changes as well, making it an ideal candidate for our project. It also sets up quickly, taking only about a day or two to fully cure.

Supplemental Power Supply: While the TEC can draw power from the computer's main power supply, this is not a good idea. The TEC draws exclusively from the +12V line and can quickly overstress this output of many off-the-shelf PC power supplies. A more reliable solution is to install a supplemental power supply with just enough power to run the TEC and therefore electrically isolate it from the remainder of our computer's components. The S320-12 Kit from Swiftech is made to be installed into a standard 5.25-inch drive bay. It also comes with a relay switch and AC socket adapter for the input power cord to plug into.

CPU Waterblock: While there's nothing set in stone that says you must use water-cooling with a TEC, they work much better this way. Due to the rapid build-up of heat at the TEC, an air-cooling system will have a hard time keeping up. So, to enable the TEC to reach maximum efficiency, you'll want to add a water-cooling system. The Apogee GT from Swiftech is an excellent product with a good price/performance ratio.

GPU Waterblock: Swiftech has introduced a kit made especially for TEC applications. The company's MCW60-T Thermoelectric VGA Waterblock is the product of choice, both for its performance and ease of installation. For the high-performance enthusiast, Swiftech also makes waterblocks for memory modules and motherboard chipsets. You may want to include these products if your speed-needy customers have the budget to support this additional expense.

Radiator: The radiator in a computer serves the same purpose as the radiator in your car: It act as a heat exchanger for the liquid coolant flowing through the pipes. The unit of choice here is Thermaltake's AquaBay M2 120mm CL-W0021, which conveniently fits in a standard 5.25-inch drive bay.

Reservoir: You need a place to keep your coolant, and that place is a coolant reservoir. For this application, a good match is the Swiftech MCRES-1000P. This kit mounts in a standard 5.25-inch drive bay, and it holds the pump as well as the coolant reservoir. (While the link above says this reservoir product is "discontinued," I urge you to find the same one for sale from another store online, at least until Swiftech comes up with an appropriate replacement.)

Pump: Moving the coolant through the system is done with a water pump. More specifically, you need an in-line 12V DC electric pump such as Swiftech's MCP350. This is an excellent match for the components we're working with here. Other models offer higher flow rates, should that become necessary.

Tubing: This carries the coolant as it travels throughout the system. For this Recipe, 3/8-inch inside diameter (I.D.) will be adequate. But if you are increasing the flow rates, you will want 1/2-inch I.D. tubing. I recommend any good, clear flexible tubing such as PVC material. Clear tubing helps, since it allows you to easily see the flow of coolant. This added visibility, in turn, makes it easier to test, troubleshoot and monitor the system.

Coolant Additive: This improves heat transfer and reduces any build-ups of foreign materials while preventing oxidation inside the system. Swiftech's product, called HydrX, is highly recommended. HydrX should be included with the Swiftech kits discussed above. If it isn't, you can purchase this additive separately online. SEVEN STEPS TO COOL HEAVEN

OK, let's get started. Follow these seven simple steps, and you'll be on your way to building out a hot system that keeps its cool.

• Prepare CPU socket, install CPU chip, and install TEC and waterblock:
• Before you drop the CPU in and start putting this thing together, you've got some preparatory work to do. First, prepare the CPU socket and surrounding areas to prevent the infiltration of condensation. Begin by using the liquid conformance coating to create a barrier around the socket. Remember to cover the small square area inside the socket, as well.
• While working around the CPU socket itself, you may want to apply the conformance coating with a brush. Once that is done, mask off other areas using your aerosol can. At this point, you'll want to set aside your motherboard and let the coating dry thoroughly before proceeding. A couple of days should suffice.
• It will help to also spray some coating on the underside of the motherboard where the pins protrude from the CPU socket(s). Another handy trick is to use silicone rubber adhesive sealant around your gaskets to make sure you get a complete seal that is as close to airtight as possible. Be sure to use silicone, not epoxy: Silicone can be removed later, but epoxy is permanent!
• When you're ready, continue by cutting a neoprene gasket to fit around the CPU socket. The easiest way: use the neoprene sheets that come with adhesive on one side. This way, you simply cut it to shape, peel off the backing, and stick it to the motherboard. Remember to cut a "donut hole" to cover the area inside the CPU socket. You don't want to leave the area inside the CPU socket exposed. The idea here is to get as much of an airtight seal as possible around the CPU socket, to keep out water vapor, thereby preventing condensation.
• Next, apply a light coating of dielectric grease to the pin holes in the CPU socket itself. Then drop the CPU chip into place, and lock it down. Then cut another neoprene gasket to fit around the CPU chip, and put it into place. Create several layers of neoprene gaskets here, making sure you cover everything from the socket to the chip to the copper cold plate to the TEC.
• Next, apply some thermal grease to the top of the CPU chip. Set the copper cold plate in place. Cut another neoprene gasket, set that one down, and put more thermal grease on top of the copper cold plate.
• Install the actual TEC unit, and put a neoprene gasket around it. Another application of thermal grease will prepare the surface of the TEC to accept the waterblock.
• Attach the waterblock to the motherboard. Caution: Do not apply too much pressure in one area at any given time. Instead, tighten one screw a little, then tighten the next screw a little, and so on. Continue in this fashion, gently tightening the screws around the socket, until they are all secure. This method will prevent the creation of stress cracks in the motherboard.
• Install TEC and waterblock for GPU chip:
• This step is similar to what you've already done, with the exception of prepping the socket. The graphics chips are usually soldered directly to the circuit board, so you won't need your dielectric grease for this part. The Swiftech kit I specified in the ingredients section above should come with a copper cold plate and appropriate mounting hardware, as well as a gasket. Remember to use a little bit of thermal grease between the graphics chip and the copper cold plate.
• Install the radiator and fan(s):
• The Thermaltake kit I specified above is a very straightforward installation. It fits directly into a standard 5.25-inch drive bay in the computer's chassis. Simply follow the directions provided with the kit.
• Install the reservoir and pump:
• The Swiftech kit I specified in the ingredients section makes for a really slick installation of the reservoir and pump. There is a single mounting bracket that holds both the pump and the reservoir, and you should screw those into place before installing the completed assembly into another of our computer chassis' 5.25-inch drive bays.
• Connect the tubing:
• You can buy the tubing by the foot and then cut it with your utility knife to the proper length. Six to eight feet ought to be enough for one system. But I like to order a little more, in case of mistakes.
• When measuring the tubing, don't give yourself any more than is absolutely necessary. On the other hand, don't make such a tight fit that there is no "give" in your hose connections.
• Tighten the hoses at each end by using hose clamps on the fittings. If you've ever had to put a radiator hose on your car, you know exactly what to do. In fact, you can use little automotive-style stainless steel hose clamps; they're classier than the plastic ones you might get at a computer shop or hobby store.
• To make it all work well, you may need to obtain various T-connectors or in-line fittings to splice in temperature gauges or flow meters, etc. The details are up to you.
• Install supplemental power supply; connect wiring and relay:
• The Swiftech S320-12 auxiliary power supply kit I mentioned above makes this step easy. The power supply itself comes with a bracket that enables you to mount the unit into another of the 5.25-inch drive bays in the computer's chassis, simplifying installation. Also, the kit comes with the necessary relay switch to turn the auxiliary power supply on and off with the rest of your system. This is a nice touch that goes a long way toward making it a user-friendly setup.
• The bare wires from our TEC units will connect to the screw terminals on the back of this power supply unit. But be careful. If you reverse the polarity of the wiring, you will reverse the heat flow direction on the TEC. In other words, if you get it backwards, you'll be heating your CPU instead of cooling it. You can use your imagination for what will happen next!
• Also, be sure and wait until you have your water-cooling system up and running before applying power to the TEC. The TEC will heat up really fast, and this can cause problems in a hurry.
• Fill with coolant and additive; test completed system:
• The reservoir that comes with the Swiftech kit has a capacity of 10.5 ounces. That means you'll need only about a third of a bottle of coolant additive mixed in to get the right proportion of ingredients.
• Be sure to use distilled water, not tap water. You don't want any contaminants building up inside the cooling system's components over time.
• Once you've filled the reservoir and replaced the cap, make one last check of all your hose connections. Then, when you power up the computer, watch for leaks or temperature spikes that may indicate a problem. If something doesn't look right, shut down the system immediately, and begin troubleshooting.

TIPS AND TRICKS

These advanced tips and tricks can help system builders during the build:

• Use a full tower chassis for your computer. This will ensure that you have enough available drive bays and enough room inside the chassis to work with while running tubing and adding peripherals.
• Match up your power demand with your power supply. The TEC for your graphics chip consumes 9.3A @ +12V, and our auxiliary power supply has an output of 25A @ +12V. This means you need to make sure the TEC unit on our CPU does not consume any more than about 15A @ +12V. Otherwise, it will put too much load on the power supply.
• To add even more cooling capacity to the system, here are some options: add an additional radiator; use larger, 1/2-inch I.D. tubing; and run a pump with a higher flow rate, such as Swiftech's MCP355. You may also consider putting each TEC unit on its own water-cooling system. This will prevent overloading the capacity of the single radiator used here. There are also higher-wattage auxiliary power supplies and TEC units available for alternative applications.
• Consider adding monitoring devices that alert the user to changes in water level, water temperature, and water-flow rates. What is airtight and waterproof today might not remain so in a month or a year from now. Water-cooled systems should be continually monitored to make sure everything is working properly. These monitors are readily available online.
• Be careful and take your time. If you accidentally damage or improperly install the CPU chips or motherboards, you will likely void the manufacturer's warranty on those parts. Easy does it.

So there you have the basics of installing a thermoelectric cooling system for a high-performance PC.

You should be able to procure all the components in the ingredients list for less than $650 total. Also, by using parts and kits from just one manufacturer (in this case, Swiftech), you'll minimize the amount of fabrication needed. This, in turn, should improve your ease of installation and the reliability of your final system.

Stay cool!

DAVID GILBERT is the owner of Appalachian Computer Systems, a West Virginia system builder that specializes in multiprocessor SCSI RAID servers.