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In The Lab
Put Water In Your Case
by chris

Water cooling vs. air cooling - which is better? Just so you know where I stand, let me just say "It depends." When dealing with cooling computer CPUs or other hardware, there are going to be trade-offs with either. As the performance and amount of equipment increases inside the case, the amount of heat being generated also increases. To increase the amount of heat that can be transferred from just one component, the surface area of the heat sink must increase or the amount of air moving across it must increase, or both. To move more air, you can use a larger or faster fan, but this will almost always result in more noise. Besides removing excess heat from the components, it is also necessary to move the heated air out and pull cooler air in to the case. If you add additional fans to do this, the noise level is bound to go up as a result. Liquid cooling kits avoid this escalation by transferring the heat into water based coolant through one or more heat sink blocks and transporting it to a radiator. The only fans required are to move air across the radiator, and even those can be eliminated by using a passive cooling tower instead of a smaller radiator.

Air cooling options: fans, heatsinks and cooling towers
Air cooling options: fans, heatsinks and cooling

Water cooling components: pump, CPU and GPU coolers, reservior and radiator
Water cooling components: pump, CPU and GPU coolers, reservoir and radiator

Many of the high efficiency after market air-cool heat sinks use heat pipes to conduct heat away from a heavy metal plate and into the cooling fins. The heat pipes allow for more and larger fins than could be attached directly to the base plate. A side benefit to increased fin size is that it can create a base to attach larger, slower-running fans, which generate less noise while moving the same amount of air as a high-speed, small-diameter fan.

A basic water cooling kit will contain a pump, radiator, and heat transfer block. A reservoir may not be required, since you still need some sort of fill tube to add the water to the system in the first place. A basic kit can be expanded by adding additional lengths of tubing and additional chip coolers. Heat exchangers are available for the CPU, video card, motherboard chipset, and even hard drives. Fluid reservoirs can be small cylinders that attach near the fill tube, or larger containers that can be installed inside a drive bay. One reason for a reservoir is to replace fluid levels as small air bubbles work their way out through the system. There should not be much loss by evaporation since the water cool system is basically a closed loop. Leakage can be a definite concern, but generally only if you were careless, had damaged or improperly fitted hose connections, tried to make changes after assembly, or if you forgot to tighten and seal all fittings according to the manufacturer's directions.

Points to consider when selecting a cooling solution:

  1. Installation - What's involved in installing the kit in your system? Most heat sinks attach directly to the system board, socket, or an existing frame. Many liquid-cool solutions and some air-cool heat sink and fan assemblies require a support plate placed on the back of the system board to support the extra weight or to distribute strain from the hoses. To install such a product as an upgrade to an existing system, you may need to remove the system board to install the back plate.
  2. Performance and Efficiency - High performance CPUs, graphics cards and other components all generate heat, and lots of it. Reliable cooling is necessary to prevent overheating and premature failure or failsafe shutdown. Air cool heat sinks and fans must be larger and have enough surface area to radiate the heat generated by the component. If you overclock your CPU or other components, more heat may be generated than what might be handled by standard cooling heat sink and fan solutions.
  3. Noise - Bigger or faster fans are the direct method of moving more air across the heat sink surface area. Larger fans may move more air without noticeably increasing noise levels, but faster fans are going to create more noise even with improved designs. Water cool systems are virtually noiseless, at least until you get to the radiator to exhaust the heat collected by the liquid. Fanless cooling towers are one solution; otherwise a large, low-RPM fan is still needed to move air through the radiator.
  4. Appearance - If you are stylizing the case or contents, the "cool factor" of glowing LED fans on the heat sink must be compared to glowing fluid-filled hoses running between the components.
  5. Space - Water-cool solutions will require more space for a liquid reservoir, a pump, a radiator, the heat exchanger(s) and hose. Air-cooled heatsink and fans will be self contained, although many of the high-performance units extend several inches above the device being cooled. With CPUs, this means you may have to remove intake ducts or other components projecting into its "airspace." Video card coolers can block adjacent slots, or reduce clearance of cables or components on neighboring adapters. If you use a passive cooling tower to reduce the noise, you are trading off noise for desk or floor space, and you also further limit the system's portability.
  6. Cost - If the components you are trying to protect from overheating are top-of-the-line devices, cost should not be a major factor compared to the cost of the components themselves. Simple water-cool kits can cost more than $300, but even a high-performance air-cool heatsink and fan kit is usually well under $100. Air-cool solutions require a separate heatsink and fan kit for each component. It is a relatively simple change to add additional heat exchange blocks to use the same water cool system to chill the system board chipset, hard drives, and video card.

For my latest system build, I am starting with an Intel D945PSN system board with 2GB of DDR2 RAM and an Intel Pentium D 820 (Dual Core) CPU. The boxed processor includes a fan-heatsink solution, but I'm getting a bit annoyed with the CPU fan noise when playing games, editing video, or doing other "high-load" activities. Other heat sources include a pair of Samsung 250GB SATA hard drives configured for RAID mirroring and a GeForce 6600 PCIe video card. (HDD RAID support is achieved with a SIIG Serial ATA II PCIe Raid card; the Intel board only has a single IDE connector and 4 SATA connectors.) By using a water cooling solution, all of these devices will be easily cooled by single radiator.

Top case modifications
Top case modifications

To make things interesting, I will attempt to pack everything into a mid-tower NZXT Trinity Gaming Case – but some modifications and compromises will be necessary. For example, the Danger Den Xtreme 2 Radiator is constructed to use two 120mm fans to push (or pull) air across the fins. I found only one case that would handle two 120mm fans in the rear, but it did not have enough clearance for the radiator to be attached to the fans. Alternative solutions to handle the double-wide radiator would include mounting it to the side panel or external to the case. A side-panel solution might work, but it would crowd the card slots or drive bays and reduce movement of the side access panel. Any external mounting is going to require that vent and hose holes will have to be cut. I finally settled on a top-of-the-case mounting location, sacrificing at least one upper 5.25" drive bay.

I will be installing a set of Danger Den cooling components which are equipped with high-volume 1/2" Internal Diameter connections. The specific water cool components used in the system are listed at the end of the article.

To prepare for installation, I temporarily installed the motherboard, power supply and drives in the case to make sure that I had clearance for the various chip coolers and hose runs. With the radiator mounted on the top of the case, the fill port must be positioned at least as high to prevent shooting coolant back out like an artesian well. The small cylindrical fillport reservoir solves this problem by sticking up just above the radiator top. After checking positions, all components were removed from the case, stripping it down to the steel shell.

Two 120mm fan holes, holes for the radiator coolant hoses, and a hole for the reservoir hose all were cut in the top case panel. Mounting holes for the fans were marked and drilled, and then two black and chrome, low-noise are fans were mounted inside the case. The normal mounting for the radiator and fans would be to attach the two fans to the radiator with small metal screws, and then either attach the radiator to the case using holes on the opposite side, or by mounting the two fans to the case from their open side. I cheated by gluing a couple of very powerful magnets to the hose side of the radiator (The radiator is all copper - so epoxy was required; obviously, this won't work if you have a plastic or aluminum case.) The magnets hold the radiator tight to the steel case, but allow easy adjustment or lifting it to attach the hose clamps. For the reservoir, double-sided foam mounting tape holds this securely in place once the hose has been attached.

View with all the hoses in place
View with all the hoses in place

Next, all the components need to be installed with the chip coolers attached. Depending on your CPU and socket type, you may have to attach threaded bolts to the system board or to a rear support plate before installing the system board in the case. The heat sink from the video card must be removed and the GPU cooler installed, again with a rear support plate. Two hard drives are mounted in the left and right drive cooling blocks, with a small section of pre-cut hose mounted between the two. With the cooling blocks in place, the drive assembly will fit in two 5.25" drive bays; I chose to remove the lower 3.5" drive rack and mount the whole kit directly to the rear of the case. Once all components are in position, you can start to run the hose. In a simple assembly with just a CPU cooler, you will want to run the hose from the pump out-flow to the cooler, from the cooler to the radiator, and from the radiator to the pump's in-flow. You will need at least two "T" or "Y" connectors to allow you to tap in a fill-port (preferable with a reservoir) and a second connection to some sort of drain. Both taps should be on the output side of the CPU cooler. Since I have a video GPU cooler and hard drive cooler, I ran the CPU out to the GPU in, the GPU out to the HDD in (with a tap to the drain), and the HDD out to the radiator in. The radiator out connection and fill port tap return to the pump.

With all the hoses is in place, it's time for a leak test - I found the radiator clamps were not tight enough, and replaced them with screw-down stainless steel hose clamps. Everything else was fine, and ready for a flow test and air bleeding. Instead of running the fill tube to the bottom, I tapped into the line just before the pump, to be able to capture bubbles as they pass by. (Some system tilting is required.) I don't really want to be running the system until I get most of the air out. If an air bubble gets trapped in one of the cooling blocks, a hot spot could develop. To remove the air, I connected the pump to an external power supply, so the system is off through the entire process. As the excess air gets passed up the line to the reservoir, just continue to add additional coolant to keep it topped off. Once most of the air is out of the lines, I reconnect the pump motor to the internal power connection (one of the Molex drive connections), and am ready to start installing the OS and software.

Glowing coolant
Glowing coolant in the
finished system

The NZXT Trinity Gaming Case features a front panel temperature meter with a small probe you can position in the case; I tucked mine in next to the CPU mounting socket. It's reading about 35 degrees C. This is almost 10 degrees cooler than a similar system running with an air-cool heat sink fan assembly. I think this is a bit lower than reality just because the probe is not under or directly touching the CPU, but it should not be too far off. The best feature of a water cool solution has got to be the noise level. You have to get right next to the case to hear the fans, the loudest one being the 80mm side mount fan. This is not really necessary to cool the system, but it lights up my cool dragon grill cover. The blue LEDs in the side fan and two radiator fans are enough to light up the UV coolant. Besides adding interest, it serves as a visual check for air bubbles in the line or CPU block.

NZXT Trinity Gaming Case
SIIG Serial ATA II PCIe Raid Card
Danger Den TDX 775 CPU Cooler
Danger Den Maze4 GPU Cooler
Danger Den Aqua Drive-2 Hard Drive Cooler
Danger Den Fillport Reservoir
Danger Den Silver Cooling System Fillport
Danger Den D5 12V Water Pump
Danger Den Black Ice Xflow Xtreme 2 Radiator
Danger Den ClearFlex 60 Tubing
Danger Den Adjustable Hose Clamps
Danger Den Dye Lite UV Reflective Water Additive

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