The Power Struggle

Pages: 1 2

Thermal Issues

Another big contributor to system instability is excessive heat. As stated in the opening section, processors are now drawing more power than ever before. The AMD K6-233 draws a whopping 28 Watts! Let’s face it, when you add more transistors, your power requirements go up and therefore the heat dissipation goes up. Some of this is alleviated when smaller circuits are used, such as the recently developed .25 micron technology. Unfortunately more and more transistors will be used as speed and functionality are increased, driving the power requirements up again in the near future, perhaps to even greater levels than before.

Symptoms of overheating can be very similar to insufficient power – spontaneous reboots, lockups and software crashes. This problem can be much more damaging to your system. Motherboards and CPUs can be permanently damaged by excessive heat buildup, especially over prolonged periods of time. Using the formula R=V/I, we can see that if current is constant (such as in a processor), decreasing the voltage can reduce the resistance – and therefore the heat. Keep in mind, however, in order for the processor to function properly, you need to keep the voltages within the specified ranges which limits your ability to regulate heat.

With the most power-hungry processors (K6-233, 6x86MX PR233, etc.) you will find that the heat generated is *much* greater than the older Pentiums and 486 chips. As a result, the need for very high quality heatsinks is apparent. There are a number of quality heatsink/fan manufacturers, and the cost is fairly reasonable considering what you are protecting. Bottom line is: don’t trust your system to an old Pentium ball-bearing fan that was not designed for today’s processors. Saving a few dollars today may mean spending a lot more later

One common practice that is advocated by the overclocking crowd is to ‘bump up’ the voltage at higher clock speeds to get better stability. This works because in order to make the transistors work faster, they need to be fed more power! Unfortunately this means more resistance, and therefore more heat. To prevent damage to the CPU and other components, it is absolutely imperative to have proper cooling.

Many people have been advocating the Thermoelectric coolers (Peltier type) for quite some time, however our testing has shown that these units cause other problems. Because these units require power to operate, they actually generate some heat on their own. Therefore, not only do they need to dissipate the heat produced by the processor, but the heat generated by their own functioning!! In addition, the more heat that needs to be dissipated from the CPU, the greater the power requirements of the cooling unit. The power requirments for these units is so high that when trying to cool a K6-233 the power supply usually can’t handle it!! (so now we are back to the first part of this article). This usually results in the unit not cooling properly, and the system overheats anyway.

A much better cooling solution is to use a very high quality heatsink with a high speed ball-bearing fan attached. Actually, the only reason a ball bearing fan is recommended is for longer life, not necessarily because it moves more air. Air movement is dependent upon the number of fan blades, the rotation speed and the fan blade design. The reality is that the *real* heat dissipation is performed by the heatsink. The fan only creates an airflow which draws the heat off the heatsink fins into the surrounding airspace.

Another misconception is that a secondary case fan will always provide better cooling than a single fan over the CPU. This *may* be true, but it depends upon how the case is designed and how the two fans work. Consider again that the reason for the CPU fan is to draw heat from the heatsink fins. This means that the air must be drawn in from the top of the fan, and blow down across the heatsink fins and out into the ambient air. If a secondary case fan disturbs the airflow into the top of the CPU fan, or prevents the air from flowing properly out from the heatsink fins, it is actually doing more harm than good. When adding any additional fans, you must first understand what the proper airflow should be, and design your solution to maximize the cooling, not hinder it.

Recommendations

When considering items for purchase, we recommend that you follow these guidelines:

  • When purchasing a case, make sure that the PS is UL approved (there is also another symbol that looks like a stylized RU which is the equivalent of UL approval).
  • Make sure that you have, or purchase, a good quality heatsink/fan for your processor. Quality manufacturers are Aavid, Thermalloy, CoolerMaster and several others. Note, however, that not all heatsinks are made equal. Get the best unit you can afford so it will be useful for future upgrades. If you don’t know, most of the manufacturers have a website where additional information can be obtained.

If you find that you are having problems with a new motherboard, CPU, etc., you should check a few things out before calling tech support. If purchased from us we are going to ask that you do these things first anyway, so you might save some time and frustration by having the information for us when you call:

  • Have the PS tested to be sure it is putting out the proper voltages and can supply the necessary power. One simple test is to disconnect *all* devices (including hard drive and floppy), and see if it boots to where it is looking for a boot device. Add devices one at a time until the symptoms start – which is likely the point at which your power supply begins to fail
  • Check the temperature of your CPU. If it is too hot to touch, you need a better heatsink/fan. Don’t try to be cheap, as the difference between a quality heatsink/fan and a crappy one is less than $10.00

Pages: « Prev  1 2  

Be the first to discuss this article!