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| Exos Liquid Cooling Sytem |
| Written by Chris Tangora | ||||||||||||||||||
| Monday, 06 November 2006 | ||||||||||||||||||
Liquid cool!
 As a general rule of computing, the faster your processor, the hotter it runs. Some exceptions can be made for CPU design, but for the most part this rule is accepted by all overclockers. Modern computer systems are designed with specific size fans and specific air flow capacities for the hardware installed. This air cooled method cools the individual components of the system (CPU, RAM, graphics cards, etc). For example, the frame of the G4 Sawtooth would have a hard time cycling enough air to run a G5 chip in the frame. Overclockers and moders have run into this problem time and time again. For Mac, moders the only solution has been to either increase the size of the heatsink and/or increase the volume of air the fan can handle. Well, no more. I'd like to welcome all the Mac users liquid cooling. For years liquid cooling has been open to the x86 market and to die hard--build-an-entire-liquid-cooling-kit-from-scratch--Mac modders. The G5 was Apple's first introduction to liquid cooling, and now it can be done by overclockers and modders everywhere with the Koolance EXOS External Liquid Cooling System from Vintage Computers of California. Vintage Computers offers a wide variety of liquid cooling options, and if your Mac does not fit the specs, they also offer liquid cooling kits for the more popular CPU upgrade cards. Components of Koolance EXOS-LT System Vintage Computer's line of Koolance EXOS liquid cooling systems run between $250 and $430 per set and can accommodate most processors; the system tested cost $369.95. My 733 MHz G4 did fall into the "not supported category," so I installed it on top of a 1.33 GHz Sonnet CPU card, also available from their site (removing the heatsink can void the warranty, but you already knew that). If you are not familiar with liquid cooling, here's a quick intro. The computer's processor makes alot of heat. Standard computer design has a metal plate (heatsink) touching the CPU with thermal paste to dispense the heat onto the attached radiator arms. A fan blows or sucks air across the heatsink arms, thus removing the heat from the processor (this is the same for advanced graphics cards). Liquid cooling systems work in much the same way, but are much more efficient. Rather than have a heatsink with radiator arms for air to blow over, the liquid cooling systems attach a metal plate and heat exchange chamber on top of the CPU, much like a standard heatsink is attached. The quality of the metal plate and heat exchange plays a big part in how efficient the system will work. A metal plate that can transfer heat quickly will be able to remove the heat from the processor faster. The heat exchange chamber is basically a sealed chamber on top of another metal plate with an in and out tube. A pump system pushes the liquid from a reservoir into a heat exchange and then receives the coolant back, where it is cooled through a radiator. 
The combined heat plate and the CPU board, the heat exchange is attached on top the metal plate.
The heat plate and the CPU board, separated during uninstalling (thermal past shows where CPU makes contact with plate)
Why go liquid? To understand why to go liquid you have to understand why you want to move away from air cooling. For standard heat dispersion to get a high amount of airflow required a larger heatsink. Take a look at the difference between a 733 MHz G4 and a 400 MHz G4 heatsinks bellow. The 733's heatsink has more surface area than the 400, allowing more airflow to remove heat. Better temperature management can be done with a liquid cooling system, since the volume required is dramatically less. You will be able to cool your system quicker as your processor runs hotter (either processor intensive tasks or an overclocked CPU). There is also an added concern for our friends in the mountains. The higher your elevation, the worse an air cooled system performs. So if you live in Denver, a liquid cooling system will have even more dramatic effect than if you live in Key West. 
The more heat, the more surface area is need on a traditional air cooled system.
Liquid cooling strengths lies in, well, the liquid. Here's a quick physics lesson to help understand why. Liquid (for this example, water) has a general higher mass and specific heat than air (specific heat is the amount of heat required to raise the temperature one degree Celsius). Water's higher density and specific heat allows it to absorb more heat, faster than air. To cool 100 watts of heat from a G5 requires 7.9 liters / second of air flow, as compared to .0024 liters / second of water flow. So a liquid cooled system not only can absorb more heat than an air cooled system, it also removes the heat quicker. (If you want to get super techie, leave a comment and I'll explain more) 
The heat exchange primed on top of the heat plate and CPU.
Liquid cooling simply takes the heat away faster than air cooling can. First because of the physical properties of liquid and second because you can separate the heat from the CPU from the rest of the computer. By having an external radiator for a liquid cooled system you can use the room air as the cooling air, you can even put it under a HVAC vent for it to grab the coldest air available (as opposed to the air in and around the computer which tends to be warmer). Liquid cooling doesn't have to stop at the CPU. You can plug in multiple heat exchange units to the different parts of a computer, and setup your liquid cooling system to cool each through the same external pump / radiator. This allows you to reduce the ambient temperature in the frame. The Koolance is rated up to 4 separate heat exchanges, so you could connect multiple units to this, say a CPU, video card, and two hard drives. Remember, cooler is better! One of the nicer features of Vintage Computer's Liquid Cooling system is that you can now monitor to the temperature of your CPU. The EXOS Koolance also allows you to hardwire your computer to shut down if if the sensor reaches above 58ºC (136ºF). I did not test this as the system was going to be uninstalled after this review and the cables did not come in my package. This gives the added hardware failure protection, if the system fails to cool properly, the computer will shut down rather than fry. During my test the temperature never reached above 38ºC (100ºF), but I only kept the CPU at 60% usage for an hour or so. I might add that 38º is a very cool temperature for a CPU. The temperature is monitored on the metal plate attached to the CPU board (copper tape holds the temperature sensor down). The temperature is displayed in Fahrenheit or Celsius on the front of the radiator with a simple LCD screen. You can place the Koolance system anywhere within reason, as long as the pump is able to move the liquid easily and it is in an upright position (no 90º mounts). The system is officially rated at 1-2 meters (3 to 6 feet). It can reach that distance because the Koolance uses a dual pump system. The dual pump system is also the reason why you can connect multiple heat exchanges to a single external unit. As a side note the Koolance is an external unit, there are other manufacturers that offer internal liquid cooling systems, but that is another review and to the best of my knowledge not mac friendly yet. The tubes enter and leave your Mac through a designated PCI slot that is outfitted with a specific PCI card to allow the tubes to go through without getting cut or crimped. The Koolance EXOS cooling system gives you three different settings for the dual fan control: low, proportional, and high. The low volume keeps the fans at low speed until they reach 51º C (124º F). The proportional (and most logical) setting steadily increases the fan speed from low at 36º (97ºF) to high speed at 51ºC (124ºF). The third setting, high, is of course the radiator fans turned to full blast (which is honestly a little noisy). The simple controls on the front of the unit allows you to set which fan control you want to use and also shows if the fans are being used more than 45% power ("normal"). 
Nice and cool CPU, even when working images in Photoshop.
Liquid cooling can play a large role in overclocking older systems, but it will really be advantageous when you overclock or mod the newer Intel systems. Since the Pentium 4 chip, Intel has taken precautions about the temperature of the CPU and frame. If the temperature on the chip and/or ambient temperature of the frame reaches a certain level (depending on chip) the CPU will run at a throttled speed. This is a built-in safety precaution that is supposed to help keep your systems alive, longer. What this could mean is that your mod'ed Intel Mac will not function properly if it gets to hot. Frame / body moders will appreciate the advantages liquid cooling offers also. While the frames and bodies designed by Apple and other computer manufacturers take into account the ambient air temperature and how the system will be cooled, when you severely mod out your frame or go for heavy overclocking, you just threw conventional cooling out the window. Liquid cooling will allow moders to not worry about fans and exhaust as much as where the external placement of the cooling system can be placed. This is also a consideration for kiosks, since you have to lockup the computer at a kiosk, the cooling element could be in a well ventilated lower chamber and the computer could be in a more secure less ventilated area. Liquid cooling systems take some serious precautions and preparation. The liquid is electrically conductive and is not safe around kids. While the reservoir is sealed with a large flathead screw, the tubes are exposed and could pose a tempting pull by toddlers. When you are dealing with the installation and especially the uninstalling it is always best to error on the side of caution. Do not assume you are an expert plumber, even if you are plumber. We're talking electricity and liquid here, so be careful! 
System installed and running. I good case mod would make this look better.
With that said, the installation is very simple. Remove all the old piece of the hardware you won't need anymore: the heatsink, a PCI slot, the heatsink fan, etc (your old heatsink makes a great paper holder). Next remove the extra parts of your system, the RAM, video card and any extra PCI cards you have. This step is purely precautionary (remember the liquid and electricity warning earlier?). If there is any liquid issues with the install, you would only be replacing a motherboard at worst, as opposed to a motherboard, your RAM, video card and PCI cards. With all the old equipment out of the way and your accessories to the side, install the new hardware (the heat exchange, a few bolts, washers and hoses). Attach the temperature monitor and you are set. Prime the system by running the computer with no hard drives attached. Once the system is primed and no air is being moved through the hoses attach your hard drives, install your RAM and PCI cards, and start up your system. Some useful install tips I found helpful: label which tube is in and out with masking tape before connecting, assemble as a dry run to be sure you are using the right screws, and use a ESD band because you will be dealing with lots of electronics! One warning expressed that I did not run into was the size of the optical drive. Early Superdrives were longer than the current ones, and the length may be a problem on some older machines. Make sure you check with Vintage Computers about possible conflicts with your system before purchasing. The other thing that bugged me was that the radiator was just a little to big to sit even on top my G4. If I added in a small riser it would have been okay. 
Frontal view. It was a tad to big for my box.
Get your mod ideas ready, the liquid cooling market is now open to the Macs. This piece of hardware makes any Mac look like an industrial strength powerhouse. I did not test the liquid for black light effect, but the native color lends itself to belive it would glow similar to the PC effects we have all seen. Start saving up and you can have yours ready for the Great Mac Mod challenge of 2007! If you have any questions about the installation, or about liquid cooling in general, feel free to leave a comment bellow and I will answer it to the best of my knowledge (and anything else I can pull up off of Google). No comments about the wiring, if you were removing the insides of your Mac every other week I imagine you would have a mess of wire also.
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