Talk'n Cool'n With Joe - #1 10/6/00

Welcome to Your Forum. I am going to use this as a Question and Answer area.  I receive e-mails every day about cooling this and cooling that. Well I am going to answer them :)  In the future please E-mail questions to CoolTalk@ProCooling.com . At some point There may be a web cast version also ( working out some details). Now I am NOT an expert or a person holding a PHD in physics, or thermo dynamics, so I may be a lil off, but the theory should be correct :) hehehe  If you have a PHD or just know yer stuff, and see me screw up some fact, please email me and let me know!

Now lets get onto the Questions:

Talk'n Cool'n W/Joe Issues

Q: What do I need to do to liquid cool my cpu, and is it real expensive?

A: The Basic parts of a liquid cooling system are these:

1. Water Block - Clamps on your CPU to do the immediate heat transfer from the CPU to the coolant.
2. Pump - Some form of propulsion for the coolant to keep it circulating
3. Radiator or Heat Exchanger - This is a VERY open and user pick able item. Some people use Tranny Coolers, Car Radiators, Mini Fridges,  Full Fridges, buckets of ice.... etc.. all it must do is pull the heat away from the coolant before it reaches the CPU again
4. Hose or Tubes to connect the system together. Can be anything as long as its resistant to your coolant, and wont breakdown.
5. Coolant - The "blood" of the system. This also can be multiple things.  Most people stick with H2O and some Water Wetter. Others go with all Alcohol, or all Flourinert.

Prices for a good entry level cooling system is some where around 50 - 100$ ( in some cases cheaper then a Heat sink and fan.)

Q: I have a H2O cooling rig, and it keeps the CPU right around where my old top end Alpha did, Why is water cooling better? I don't see it.

A: Water cooling vs Forced air cooling is an argument of the ages.   All the way back to the first internal combustion engines.

Forced Air cooling is good for most cases but you are limited by the max heat dissipation in a given area in a case, and by the size of the HSF. If you are running a CPU that generates  80% of what that HSF can dissipate in the given ambient temp, airflow, surface area of the HSF, speed of fans.  Then if you take a H2O cooling system that can dissipate  2x more heat then the HSF you had, Strap it on and be only using 40% of the possible heat dissipation of the system.  Yet your CPU only drops a little in temp ( and remains more constant of a temp).  This is because of the ambient temp only allow the radiator to expel so much heat.  Since the temp of the coolant is being help just slightly above ambient temp ,due to the great cooling the radiator is doing,  there isn't allot lower the coolant can go then ambient + heat from the Pump + the system isn't 100% efficient.

Water cooling systems excel with more heat to dissipate. A water cooling system is NOT the best as just bringing something down to room temp in some cases, due to complexity, and extra parts in the system that loose efficiency every inch of tubes and such.  BUT if you are throwing allot of heat at a cooling solution with Peltiers, normally you would go far beyond the limits of what a Alpha could even do.   But since a Water cooling system has a much greater ability to dissipate allot of heat fast, its best suited for Peltier cooling more then CPU cooling.  The more you can heat up the coolant the more efficient the Radiator can be at exchanging the heat for cool air.    You can possibly see a Delta of -50 Degrees or more at the CPU core from the ambient temp because of how efficient the Water cooling system can take the heat from the pelt which is much greater then ambient and dispel it to the air.

This may be confusing, but the break down is simple:

Water Cooling - Can dissipate mass amounts of heat fast, and easily. Is less efficient at lower (close to Ambient) temps,  but more efficient at higher ambient temps. Because of the head room afforded by water cooling Ambient temp swings don't impact the cpu as quickly.

Forced Air Cooling - Can dissipate some heat well, but reaches a physical limits rapidly and cant compensate for high ambient temps well.

Q: Silver, Copper, Aluminum, Zinc, silicone, Toothpaste... what is a good heatsink compound??

A: This is another hotly debated topic.  A Winner has seemed to emerge.  The Silver Arctic paste that's out on many store sites, as seemed to win the hearts of most reviewers and hardcore geeks. But lets look at the others:

• Copper paste: Slightly below Silver.. but marginal at best.  I think its more about who makes the paste then its components, especially since I have seen both beat each other in different reviews ( on the same site sometimes).
• Aluminum : Also good,  but its better in the Aluminum filled Epoxies due to the heat stressed and how it expands and contracts with the aluminum in your water block.
• Silicone: Nice, cheap ,and works pretty good.  I have a Tube of DOW Corning 340 Heat sink Compound.  Its worked great on Pelts, you name it. its pretty cheap compared to the luxury pastes above
• Zinc Oxide : Pretty close to Silicone, as most are Zinc Oxide suspended in a binder like silicone.
• Toothpaste : I Sh*t you not. Because tooth paste has SOME conductive properties when wet.. people thought it was a good thing to use. ITS NOT SO DON'T.  When it drys its like putting some dry pain flakes or some sand in-between your CPU and Heatsink.... not real good conductors. ( but yer CPU will have a Minty fresh taste :)

Q: What's up with all these different cooling blocks? Polished? anodized?, small?, large?.. does it mater?

A: Jury is still out on this one.  In theory a polished outside is good.   It will aid allot in making a perfectly flat contact patch on the core of your CPU. ( reqire'n less of the silver paste saves $$$).  Those savings are fractions of a cent in reality. The Polished blocks are nice but only perform marginal at best better then the normal machined blocks.

Smooth blocks are essential to a good performance cooling product. Polishing is going to the next level and for all intents and purposes I will say you will notice no difference between one that's shiny and one that smooth and well cut.

Anodizing is the process of embedding a dye onto the surface of the Aluminum ( and under the oxide layer) The affect this extra layer of not so conductive material over your block or heat sink, the impact of this is also debatable. Since Anodizing happens in an acid bath you actual pit the Aluminum block/HSF a bit ( very very very small pits at the most).  Barely noticeable ( its at a microscopic level as it breaks down the oxide layer because of the high current bath its in)  There has been some people saying that its no affect, others swear against it.  Its only recommended if you MUST have your block Red or something to match your case. Otherwise go with an untreated bare block.
UPDATE - Correction-
"Hey joe Not too Bitch but your way off on what  Anodizing is It has nothing too do with a dye.   It is just added in the sealing process for looks Most  Anodizing is clear , Also Anodizing is Basically   Pure Aluminum Oxide What happens is you speed up the  oxidation process about 100 years and anodizing will not conduct electricity and it is a thermal Barrier  you will see about 5 degrees with it on the block  any way just thought i would fill ya in."

From - Brad Zawislak <liquid_radiation@yahoo.com> ( this guy knows his stuff.. I promise you that!)   Thanks Brad!

Stay away from any blocks that are sprayed with an Anti-Oxidizing coating of any kind, I have seen 2 on the market in the last year that were coated against that.... The coating is normally a diluted poly urethane based coating, a Very nice insulator.

The inside water passages in cooling blocks should NOT be polished,  keeping them "natural" as they were drilled or machined is preferable.. it will create more surface area and also more turbulence in the water and cause more molecules of coolant to hit the walls and absorb heat.

The "Pool" type blocks? These are some that swirl the water in a circle across the face of a plate or a round HS inside, these are the most effective and efficient of any design I have seen yet.  Not much data on these yet though.

Size BARELY matters in blocks. get one that's big enough for a Pelt,  and can move a good amount of coolant through it.. and that's all that matters as far as size goes.

Q: I am going to be cooling a Celeron 566, I want to go to 1Ghz, should I go with a Car Radiator for something like that?

A: Simple Question - Simple answer :

No, a car radiator is meant to cool something that puts off hundreds of thousands of BTU's of heat potentially, and keeps it around 150 Deg+  Your CPU puts out like 20 - 40 Watts of heat at the absolute MAX of most any CPU. Get a radiator that can work in a smaller scale.  Like a motor cycle radiator,  tranny cooler,  or some specialty coolers from online stores.

Q: How many GPH should my pump be?

A: Depends on your setup, Tubing lengths, radiator size, and elevations you want to move the coolant.  most people can get away with a 60 - 100 GPH lil pump for an In case cooling system.  For a larger outside cooling system 100 - 350 is good.

The diameter of your lines has more impact on speed and volume of your coolant then the pump. Before you buy a new pump to get more coolant go from 1/4" tube to 3/8" tube atleast. If you Double the Inside Diameter of the tube it will decrease resistance on your coolant by a power of 16!!!!

The Monster pumps of 600+ are not of much use for these systems. Unless you are running a back bone for multiple systems, 600GPH is nothing but a big heat producing device that's being over stressed cause of the small loop and restrictions of the tubes..

Well Guys that's all I got time for tonight, Enjoy and send in your questions! if I cant answer em I will find someone who can! Check back at ProCooling.com for your questions to be posted in the next issue of Talk'n Cool'n with Joe.

Take Care,

Joe