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More Power, Scotty!!
As processors have become more powerful, their power requirements have increased also. Faster memory, hard drives, CDROMs and Video cards also draw more power due to more electronic components and faster motors. In addition, people are loading up their systems with scanners, removable drives, video editing cards, TV cards and other devices as technology delivers more and more wonderous products. Those who engage in overclocking can drive this power requirement much higher. With this increase in power requirements has come a new set of problems, including increased heat dissipation and system instability due to insufficient power supplies.
Since semiconductors are designed to work within a relatively narrow range of temperatures, thermal management is becoming a very important issue. A simple search of the various hardware newsgroups will reveal a high percentage of posts relating to this subject. We have also noticed that quite a high percentage of older power supplies (and even a lot of new ones) are simply not capable of delivering the power necessary to drive these new, powerful devices.
To understand these issues, we must first gain a basic understanding of the terminology, and the basic formulas of electricity. In order to generate electrical power, you must have two factors – voltage and current. Voltage is the electrical ‘potential’, while current is the actual ‘flow’. You can make the analogy of a water hose, where voltage would be the amount of water that can be ‘pushed’ at one time (diameter of the hose), and current would be how fast the water is being pushed through the hose. While there may be water in the hose, until there is current (or flow) there can be no work performed.
The amount of work potential (or power) is determined by both voltage and current. Therefore, for a given voltage, more current must be applied to generate more power. Conversely, the current can be lowered by increasing the voltage for a given power consumption. The *actual* work performed is determined by how much time has passed, such as KWh (Kilowatt hours). A good analogy to this might be a car engine that has a lot of potential (horsepower), but work is only performed when measured over time (miles per hour).
Another factor to consider in electrical circuits is resistance, which is anything that obstructs the flow of current. You can think of resistance as friction – the greater the friction, the more heat is generated. For example, a light bulb is basically a piece of tungsten wire that has high resistance. This resistance causes the wire to heat up to a point where it begins to glow. Lightbulbs with different ‘wattages’ are basically determined by how much current is necessary to make the wire glow, since the voltage is constant. Note that the amount of resistance is determined by voltage (R=V/I), but the greater the current the more heat is generated from that friction.
Your most important component
One of the most difficult problems to diagnose has been the insufficient power supply. Symptoms can range anywhere from a ‘dead’ board, to frequent lockups to software crashes. These symptoms take on the appearance of motherboard, CPU or memory problems. Sometimes it can even look like a bad hard drive, CDROM, floppy drive, etc. As it turns out, a very large percentage of products returned as defective have absolutely no problems at all and many times it turns out that the power supply was at fault.
Consider that virtually *every* component in your system gets it’s power from one source – the power supply. That power supply must provide a smooth, consistent flow of power to all devices at all times. If there is a power surge or insufficient power from any or all of the outputs, the specific device attached to that plug can appear to be defective. Memory can fail to be refreshed and lose data (causing a software failure), the CPU can lock up or spontaneously reboot, the hard drive can fail to spin up – or even more strange, spin up but fail to respond to any input signals giving the appearance of a ‘crashed’ hard drive. The list of symptoms is very long.
Since there are so many components that are dependent upon this power supply, I would consider it to be the *most* important component in your entire system. Unfortunately, the majority of people rarely even consider the power supply as a factor in their purchasing decisions. Many people are upgrading from their old 486 machine, or purchased a case and PS from a local computer show, then expect it to support the most powerful and advanced hardware available.
In our experience, this is probably the single most common problem today. Older power supplies may not be as efficient as they were when new, and are not actually putting out the power they were originally rated for. Many cheap, generic cases do not have UL approved power supplies, and are probably putting out only 50-75% of the power they have printed on them. Even well-known quality cases can have problems with power supplies. We heard from one customer who had to replace the PS in his brand-new Enlight case 3 times before he found one that would support his components.
In fact, we were told by one large distributor that a well known Southern California electronics retailer purchased a number of cases with full knowledge that the power supplies were only putting out about 110 watts (though they were marked as 250W). Though the distributor intended to send the cases back (overseas) for replacement, the buyer simply offered to take the cases off the distributor’s hands at ‘cost’ so they could save the shipping costs back to Taiwan, with the explanation that the retailer would be able to get rid of them because most people wouldn’t know the difference!!.
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