How Liquid-cooled PCs Work

Whether you're using a desktop or laptop computer, there's a good chance that if you stop what you're doing and listen carefully, you'll hear the whirring of a small fan. If your computer has a high-end video card and lots of processing power, you might even hear more than one.

In most computers, fans do a pretty good job of keeping electronic components cool. But for people who want to use high-end hardware or coax their PCs into running faster, a fan might not have enough power for the job. If a computer generates too much heat, liquid cooling, also known as water cooling, can be a better solution. It might seem a little counterintuitive to put liquids near delicate electronic equipment, but cooling with water is far more efficient than cooling with air.

Image courtesy Darrin Gatewood A liquid-cooled PC in a clear case. See more liquid-cooled PC pictures.

A liquid-cooling system for a PC works a lot like the cooling system of a car. Both take advantage of a basic principle of thermodynamics - that heat moves from warmer objects to cooler objects. As the cooler object gets warmer, the warmer object gets cooler. You can experience this principle firsthand by putting your hand flat on a cool spot on your desk for several seconds. When you lift your hand, your palm will be a little cooler, and the spot where your hand was will be a little warmer.

Liquid cooling is a very common process. A car's cooling system circulates water, usually mixed with antifreeze, through the engine. Hot surfaces in the engine warm the water, cooling themselves off in the process.

Click on "Start" to see the fluid flow through the engine as the engine warms up.

The water circulates from the engine to the radiator, a system of fins and tubes with a lot of exterior surface area. Heat moves from the hot water to the radiator, causing the water to cool off. The cool water then heads back to the engine. At the same time, a fan moves air over the outside of the radiator. The radiator warms the air, cooling itself off at the same time. In this way, the engine's heat moves out of the cooling system and into the surrounding air. Without the radiator's surfaces making contact with the air and dispelling the heat, the system would just move the heat around instead of getting rid of it.

A car engine generates heat as a byproduct of burning fuel. Computer components, on the other hand, generate heat as a byproduct of moving electrons around. A computer's microchips are full of electrical transistors, which are basically electrical switches that are either on or off. As transistors change their states between on and off, electricity moves around in the microchip. The more transistors a chip contains and the faster they change states, the hotter the chip gets. Like a car engine, if the chip gets too hot, it will fail.

Most computers dispel this heat with heat sinks and fans. Heat sinks are basically pieces of metal that provide lots of surface area for the air to touch. The chip warms the heat sink, the heat sink warms the air, and the fan moves the warm air out of the PC case.

Image courtesy HowStuffWorks Shopper A heat sink uses lots of surface area to transfer heat from electronic components to the air.

This system works most of the time, but sometimes, electronic components produce more heat than simple air circulation can dispel. High-end chips with lots of transistors can overwhelm an air-cooling system. So can chips that have been overclocked, or manually set to work at faster than their default speed.

Cooling with a Terminator T-1000 In 2005, computing magazines reported that a liquid-metal cooled graphics card called the Radeon Blizzard X850XTPE would soon hit the market. Preliminary reports suggested that cooling with a liquid metal alloy was even more efficient than cooling with water. However, the card never made it to market, most likely because the cost of materials and production outweighed any improvement in cooling performance.

That's where water cooling comes in. Water has a higher thermal conductivity than air - it can move heat faster than air can. Water also has a higher specific heat capacity. It can absorb more heat before it starts to feel hot.

There are two reasons why a computer might need the increased thermal conductivity and heat capacity of water:

• Its electronic components produce more heat than the air around them can absorb
• The fans required to move enough air to cool all the components make too much noise or use too much electricity

In other words, there are two reasons why you might need to cool a computer with a liquid instead of air:

• The components inside your computer need more cooling than air alone can provide
• You want your system to be quieter

Next, we'll look at the components of a liquid-cooled system and how they work together.

All-in-one Units and Kits If you like the idea of liquid cooling but don't want to research individual components, you can buy a ready-to-use unit or kit. Self-contained units can plug directly into a computer's expansion slots or power supply and provide liquid cooling to one specific chip. Kits include all the parts you need and instructions for assembling them - just make sure the parts included are compatible with your computer's hardware. Some companies also sell high-end PCs with liquid cooling factory-installed.

How to Install RAM

Most of the time, installing RAM is a very simple and straightforward procedure. The key is to do your research. Here's what you need to know:

• How much RAM you have
• How much RAM you wish to add
• Form factor
• RAM type
• Tools needed
• Warranty
• Where it goes

RAM is usually sold in multiples of 16 megabytes: 16, 32, 64, 128, 256, 512, 1024 (which is the same as 1GB). This means that if you currently have a system with 64 MB RAM and you want at least 100 MB RAM total, then you will probably need to add another 64 MB module.

Once you know how much RAM you want, check to see what form factor (card type) you need to buy. You can find this in the manual that came with your computer, or you can contact the manufacturer. An important thing to realize is that your options will depend on the design of your computer. Most computers sold today for normal home/office use have DIMM slots. High-end systems are moving to RIMM technology, which will eventually take over in standard desktop computers as well. Since DIMM and RIMM slots look a lot alike, be very careful to make sure you know which type your computer uses. Putting the wrong type of card in a slot can cause damage to your system and ruin the card.

You will also need to know what type of RAM is required. Some computers require very specific types of RAM to operate. For example, your computer may only work with 60ns-70ns parity EDO RAM. Most computers are not quite that restrictive, but they do have limitations. For optimal performance, the RAM you add to your computer must also match the existing RAM in speed, parity and type. The most common type available today is SDRAM.

Additionally, some computers support Dual Channel RAM configuration either as an option or as a requirement. Dual Channel means that RAM modules are installed in matched pairs, so if there is a 512MB RAM card installed, there is another 512 MB card installed next to it. When Dual Channel is an optional configuration, installing RAM in matched pairs speeds up the performance of certain applications. When it's a requirement, as in computers with the Mac G5 chip(s), the computer will not function properly without matched pairs of RAM chips.

For complete guidelines on setting up Dual Channel configuration on Intel Pentium 4-based systems, check out this guide.

Before you open your computer, check to make sure you won't be voiding the warranty. Some manufacturers seal the case and request that the customer have an authorized technician install RAM. If you're set to open the case, turn off and unplug the computer. Ground yourself by using an anti-static pad or wrist strap to discharge any static electricity. Depending on your computer, you may need a screwdriver or nut-driver to open the case. Many systems sold today come in tool-less cases that use thumbscrews or a simple latch.

To install more RAM, look for memory modules on your computer's motherboard. At the left is a Macintosh G4 and on the right is a PC.

The actual installation of the memory module does not normally require any tools. RAM is installed in a series of slots on the motherboard known as the memory bank. The memory module is notched at one end so you won't be able to insert it in the wrong direction. For SIMMs and some DIMMs, you install the module by placing it in the slot at approximately a 45-degree angle. Then push it forward until it is perpendicular to the motherboard and the small metal clips at each end snap into place. If the clips do not catch properly, check to make sure the notch is at the right end and the card is firmly seated. Many DIMMs do not have metal clips; they rely on friction to hold them in place. Again, just make sure the module is firmly seated in the slot.

Once the module is installed, close the case, plug the computer back in and power it up. When the computer starts the POST, it should automatically recognize the memory. That's all there is to it!

For more information on RAM, other types of computer memory and related topics, check out the links on the next page.