LOSTCIRCUITS

To fill in some of the gaps, here is a very brief synopsis of the underlying electrotechnical background. The voltage regulators used on the RADEON 8500 (as well as on most other boards) use the ratio between a reference signal and the returned sensed (feedback) signal to determine the amount of voltage they need to output. Commonly, this is described as the ratio between two resistors, however, it is much easier and accurate to imagine the current or voltage ratio. Resistors just sit there passively, so forget about them what you or, by extension, the controller feels is the voltage, easy enough? In more detail, if the output voltage is regulated by the ratio of V1/V2 input voltages, all you need to do is increase V1 and your output voltage will increase proportionally since V2 is fixed.

A "SuperTools" pipecutter is a handy tool for any sorts of plumbing work. If you don't have it, a hacksaw will suffice to cut off a few rings of a standard 1/2" hot water pipe

Increasing the voltages, of course, results in higher thermal load which, in turn, results in reduced performance or, more importantly, stability problems because of overheating. In other words, don't do voltage increases without increased cooling for the GPU (since we already have taken care of the memory).

With the memory RAM sinks, I went the easiest way, that is brass fittings from HomeDepot. Brass is easy to work with, however, has the disadvantage of relatively poor thermal conductivity, which is slightly below aluminum and only about 1/3 of what copper offers. For the memory, this is sufficient, after all, the standard version does not even offer any heatsinks and the rather large surface area of the RAM sinks combined with quite some thermal capacitance does the rest to keep the chips in a thermally sound range.

Four rings of the pipe, slightly lower in height than the depth of the remaining bottom of the cap as shown on the last page. These rings will provide the base of the cooling fins inside of the GPU cooler.

The situation is different with the GPU. The graphics processor is already actively cooled and develops quite some heat. In other words, the goal is to increase the cooling by substituting copper and a more powerful fan for the standard cooler. Keep in mind that commercial graphics coolers have to abide by the limitation of the distance to the first PCI slot. This is no concern for us, PCI slots are usually abundant enough so that we can ignore this restriction and put on something larger (within reason).

Once again, the goal was to get the whole thing done for $10 or less and this is what it came down to:

Materials

• 1 x 1 1/2" copper pipe endcap: US$ 2.95
• 1 x 1" x 1/2" copper hot water pipe: US$ 0.70
• Solder and flow medium US$ 1.45 (still had the solder from the last plumbing job)

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