PC Cooling - Exotic Solution Research: Part 1

[Anime-Addict]

This is just a place for me to lay down my thoughts, as I begin the plunge into a series of research cycles and experiments, to determine both a bragging-rights system, and a on-the-cheap system. This is part one, where I investigate the theory behind heat transfer, and begin to apply it to theoretical systems. Your comments are more than welcome, and if you have anything you wish to add, your post is doubly appreciated. Please be aware that I may very well double post... Do not be alarmed.

The Problem...
Modern PC's need to dissipate large quantities of thermal energy. Older PC's did create as much thermal energy, thus the traditional air cooled heatsinks were sufficient. Today this heat exchanger system is still commonly used, however larger thermal output equated to either larger volumes of air being forced through the heatsink, or a larger heatsink. This results in either a unacceptably loud, or unacceptably large solution.

The Quest...
I aim for 2 discrete categories, silence and performance.

The Equipment...
The idea is to remove heat from different components, then tying them all together.

Power Supply - Usually not cooled with anything but air because of the high voltages involved.
CPU - Commonly cooled with air, but other consumer solutions available.
North/South Bridge - Commonly cooled with air, but other consumer solutions available.
CPU Driving MOSFET's - The on-the-motherboard power supply for the CPU, when driving monster CPU's can generate impressive amounts of heat.
Video Card - These power hungry devices rival CPU's in their thermal output, however they pose additional challenges with the small amount of space provided.
Dissipater/Exchanger - Gotta move this collected thermal energy somewhere...

The Mindset...
Starting at the top of the list and working our way down, I examine the possibilities...

 

[Harukalover]

QUOTE (Anime-Addict @ Oct 07 2007, 08:15 PM)I aim for 2 discrete categories, silence and performance.
Water cooling. Since there's no way in hell, that you'll get _very efficient_ cooling through air cooling without noise.

Or maybe even do something insane and use cooking oil.

Insane idea

Or even use liquid nitrogen.

Another insane idea

The possibilities are endless. @_@

 

[InuyashaX]

Is this some sort of homework or job related work? Cause it might be better to post this in the homework thread.

http://boards.fansub.tv/?showtopic=3378&hl=

Umm, well it is true PC's and even gaming consoles are having heating problems, that why the PS3 has 9 cell processors, to reduce heating. I think fans might become a thing of the past, with new advancements in technology, we might be able to make more efficent materials that dont over heat and lower the temperature inside the system through freon perhaps? But that might not work out well, its not a friendly substance.

 

[Anime-Addict]

The Power Supply - How it Works.

Many people are frightened about whats under the hood of Switched Mode Power Supplies (SMPS), and justly so, as there is mains voltage, and the supply has several components for storing electrical energy long after disconnect. First let's study how a SMPS operates. I took apart an old 300W PSU that I had scavenged the MOLEX connectors off of for an earlier project.

WARNING: Do NOT attempt to open any power supply unit without discharging the energy storage components, capacitors in particular. Better yet do not attempt this at all! If you MUST, make sure there is someone else there ready to call 911. That is how serious this is.

Now thats that is over with... Lets move on. The SMPS while appearing quite complex from the component point of view, is really quite simple, when the operation is broken down into groups.

The mains power feeds into the input rectifier and filter, it is at this stage that the red or black switch on the rear of the power supply comes into effect. If the PSU is operating in the 110V input. this switch places a transformer in the circuit to double the mains voltage to 220, if the PSU is in 220 mode, this switch removes the "voltage doubler" and the unit runs off of mains voltage. This tells me that so far, the maximum voltage I will encounter in a normally operating PSU is 220V. All of my PSU's run in 110V mode, so after exiting the voltage doubler the current is fed through a full wave rectifier. The schematic is illustrated below.

If you are not an electronics major, the full wave rectifier flips the negative portion of the AC to positive. A really clunky explanation but it will have to do. At the output side of the full wave rectifier you can see that the voltage drops back to zero 120 times a second inf the un-rectified AC was 60hz. To remedy this a "smoother" or filter is needed. Usually a large set of reservoir capacitors is used, charging as the voltage increases then supplying power when the voltage falls, repeating every cycle.

The inverter stage converts DC to AC by running it through a power oscillator, whose output transformer is very small with few windings at a frequency of tens or hundreds of kilohertz (kHz). The frequency is usually chosen to be above 20 kHz, to make it inaudible to humans as the core of the transformer deforms under magnetic stress. The output voltage is optically coupled to the input and thus very tightly controlled. The switching is implemented as a multistage (to achieve high gain) MOSFET amplifier. MOSFETs are a type of transistor with a low on-resistance and a high current-handling capacity. This section refers to the block marked "Chopper" in the block diagram.

The output is then rectified, and filtered. The output is monitored by the chopper controller, and changes the speed at which the MOSFET's switch on and off, changing the output voltage. Then Wala! You have your nice smooth DC output... Now lets look at cooling the thing with something other than air....