Active PC cooling

My teenage son has built a honking game computer over the last few months and is suffering cooling problems also. Without my knowledge, he's hooked up some ducting to bring in outside air to cool his unit, his room and eventually, the whole house. We live in Northern Canada, it's winter and wait 'till his mother finds out. But it'll be summer soon and by then you may have found some neat solutions to this situation.

hi nickjd, ..... this is not my field of expertise but a friend of my just patented a water system computer ( for serious processing ) . however he leaves in france ! if you have any interests to this info let me know ???

ht

You can put together a small Air conditioning unit using discarded refrgator units condensing units and modifie eveoporator part of he Fridge to suiet your application and run a duct for air flowinto the PC or a server if you have an existing Ac working at your place then you can tap the supply air which will meet your requirement but watch out its not just cold air you need it should be Low in Moisture for Server or PC application other wise you wood end up damaging your Hardware of the PC or Server when you attain room temperature less than ambaient ,again your cooling requirement depends on Type of server you are thinking you can achive dryness of air by passing cold air through moisture Obserbent like silica granuales which can be recycled by heating the silica granuals.

best of luck

murali

You are absolutely correct about extending the life and increasing the reliability if you keep the hardware cool but I think you are going a little overboard.

Around 12 years ago I build a control system for my house that used a PC as the core processor. I built a special enclosure with a series of thermostatically controlled fans that blew filtered air over the appropriate parts.. It only used the ambient air in the room and even where I live with temperatures rising to above 40°C there has never been a problem. It has been running 24 hours a day 365 days a year for over 12 years now and the only time it has been down is during extended power outages.

One of the big problems with most PCs is that they cool the boards by sucking the hot air out rather than blowing cool air in. The result is that it turns your PC into a vacuum cleaner that steadily becomes more clogged with dust and airborne debris. The do it this way because its easier and cheaper but it is by no means the best way to do it.

With a little bit of ducting and filtering the air before it goes through the fan you can usually keep the guts of most computers clean and cool enough with just ambient air. Of course you could got the way Cray did and put the whole thing in a bath of Freon or something similar but for home use it's a bit of an overkill.

I would have thought that a water cooled heat sink with a small pump to keep water flow would handle 300 watts no problem...

The water could be in a closed system going through a radiator with a fan blowing air through it, a few temperature sensors and electronics to monitor flow and status of cooling, that would make a nice cheap and quiet system...

Better still use an air conditioning type of cooling unit to position the radiator and fan outside...

John.

Masu

Saw your post regarding CPU cooling but am most intrigued by your house control system. I will be building this spring and I have thought about some "whiz-bang" type of controls in our new home.

Obvious concerns are reliability, initial cost, resale value and ultimately, what, in your opinion, has actually turned out to be most useful.

I am sure that you thought your way through all of this twelve years ago. Have you discussed any of this on line where I might be able to read and take advantage of your analysis?

Always appreciate your posts.

Lonnie

Hi Ishurtle,

If I were starting over I would use a carputer, or car computer, as the core for all the complex data processing and voice interface. There are a couple of reasons for this, firstly they run on 12 volts so, designing and building some sort of Uninterruptible Power Supply is much simpler, as it doesn't require the inverter to convert the 12V DC battery power back to AC. Secondly they are more robust and tolerant to heat so cooling them is much simpler.

For interfacing the system with the real world the best way to go is a Programmable Logic Controller. The reason for the PLC is that they are designed for switching and monitoring mains voltages and you can buy just about any type of interface that you can think of off the shelf. Switching mains type voltages is fraught with all sorts of problems and mistakes can be anywhere from expensive to deadly. The other thing is that you can use the PLC to do a lot of the simple control, or pre-processing, like switching lights etc and leave the complex stuff to the PC. If you hunt around and contact the local automation companies you may be able to score a second hand PLC that they have upgraded for next to nothing.

After that the sky is the limit, my system annunciates all sorts of events like somebody at the front door etc. The more sensing equipment you connect to it the more you can do. I have motion detectors connected to it and use these for numerous things. Firstly there is the obvious use as a burglar alarm but you can also use it to switch lights and control air conditioning as well. I use them with an alarm clock feature that politely announces that it is time to get up then with ever increasing sarcasm nags you every 5 minutes till it detects motion in more than 1 room so its sure you have actually gotten out of bed.

With annunciation, work out some way that varies what it says. My system has a thing I call the frustration index that measures repetition. The higher the frustration factor the more sarcastic the announcement of an event becomes. With the burglar alarm it threatens to let a couple of hungry Dobermans loose. There are normally a pair in the back yard and it's only a threat but if you were a burglar and the house you broke into threatened you with a couple of big mean hungry dobies would you stay and take the chance or clear off and find an easier place to rip off? Another trick is to have a digital camera set up to take a picture of any intruder and then automatically fax it to the nearest police station with a covering note that say your house is in the process of being burgled by the individual in the attached photograph, would you be kind and pop round and arrest them.

If you really wanted to go to extremes you could use RFID technology to keep track of who and where people are and get it to automatically unlock doors that they were aloud to go through and lock those they weren't. ultimately it up to your imagination how much you can do, and if you have a permanent internet connection the possibilities are beyond comprehension. I have however found that a certain amount of mad scientist type thinking is always a help.

One final thing is that since it talks it need a name and for a computer like this there is only one possible name so I would suggest you go with the flow and call it HAL. This is also a help if you go all the way in use voice commands as you can use the name as a trigger for it to interpret the following as some sort of instruction that needs to be interpreted.

Have fun automating and I I can be of any help don't hesitate to drop me a line.

Actually your only real alternitive to super cooling your system, is to do as the larger companies do with their computer rooms. Place your system into a sealed environment with dust filters and a chilled room per say. That is, make an enclosure for you system with an external cooling system. We have a rack mounted industrial main frame in our home office and the closet is a self contained cool room. The roo is monitored by a small portable a/c unit and has an internal T/C to the main frame unit.

The main frame unit has four 10" fans to move air from top to bottom w/ a filtration on the intakes. The cooling closet is kept at a whopping 60*F. The closet is thermally insulated to keep all this cool air in the closet and not being vented out to the rest of the office. And the closet is monitored by our main system with alarms and a small video camera so we can watch from our desk top terminal with out entrence.

Just my two cents worth in your quest to topple your friend.

We used industrial 1" dual form insulation board in the closet. It works very well as a sound deadning device too.

Have a great day.

Remove the heat sinks from the cool side of the peltier units and apply them directly to the device you are cooling, remember to use heat sink compound. You can stack peltiers to get more cooling. No heat sinks in the middle of the stack.

When I see posts of the sort I always wonder why not just get a small refrigerator the kind Wal-Mart sells for 50 bucks and put the pc in there? It's cheap, quite, and easy.

yes, I've thought about that, and even a small refrigerator could move 300 watts of heat (for a while, but wouldn't be good for it running continuously). Also, who wants to carry around a fridge to LAN games?

Nick

Take a look at Vipochill system at http://www.asetek.com/

Cooling a CPU is not as simple as it looks. CPU don't generate constant heat. Heat shoot up when there are heavy processing. The cooling system need the capacity to remove that heat fast enough. Most systems are stable for a short time due to heat soak and fail to remove heat fast enough. Water cool with large amount of coolant helps. Peltier suffer badly from heat soak since it doesn't have much heat capacity. Maybe use the peltier to cool the coolant in a water cooled system. Also water tends to condense on the cold peltier side which id bad for the system. You'll need to seal the peltier and CPU completely.

Do some search on cpu overclocking and cooling. Tom's Hardware, HardOCP are examples. People had used liquid nitrogen to get extreme OC from CPUs.

I know this sounds like a ridiculous project, but at my engineering school, we have this little unwritten unspoken contest among a few of the upperclassmen, to see who can make the most crazy computer. I agree, it looks like there would have to be a combination of water cooling and some kind of active cooling. My friends computer is a completely water cooled Athlon 64 4000+, duel GeForce 7800 GTI, w/ 2gb of ram and 1 TB of hard drive space. His computer uses something like 400 watts of power full bore (cpu uses 90 watts), and nothing in his case gets any warmer than 100 degrees F. Actually his hard drives get warmer than his CPU...

So, I want to compete with that somehow. I'm thinking it would be hard to compete with that, but still, it will be a fun project.

You can see what I did before with the pelts in a previous failed project, but I think that I would have to do something similar again, after I water cool stuff. For now, I will just buy a new case, mod it, and then this summer I will put computer parts in it.

Hi nickjd

Seems like there might be two aspects to your query. First, your computer components were probably originally designed to operate at ambient temperatures suitable for human comfort indoors with at least a little bit of headroom for safety. To get the most out of the unit--conservative overclocking, etc.--you will need to keep a lot of clean ambient temperature air moving through the unit. Best way is to over-pressurize the unit to keep dirt out and use the room as your air plenum. Then concentrate on conditioning the room environment so you don't get unacceptable heat/humidity (for both humans and computers) rise in the room. You can do this with off the shelf air conditioning either through your wall or window or through the existing ductwork.

If you wish to go a bit further, I would think the next step would be some external cooling of the air going into the cabinet, probably using a small window type air conditioner to get enough air volume. This will bring the internal environment of the unit down to a stable, cool ambience. Watch out for moisture. You should do these things for the good of your system generally. I don't however think that this is what your question is really about.

I think that your real linterest is in some how keeping your CPU cool enough to survive while you overdrive the living bejabbers out of it and blow all your competitors away! If so, I think the way to START is as I've stated above. THEN, figure out how to get the heat out of the CPU. Peltiers sound like a good way to go but you must have direct physical contact as described in a previous post--or spot water cooling--or ducted refrigerated air--some way to specifically keep the outside of the CPU very, very cool to take advantage of the heat transfer characteristic of the CPUs design. I expect some CPUs have the ability to move more heat than others and this might be a consideration for your next hotrod upgrade.

The Peltier with hot side heat exchanger exposed to the pre-cooled, over-pressurised, high-volume airflow inside the cabinet sounds good to me but there may well be physical problems with getting the cold side in direct contact with the CPU.

The final thought would be a way (because we are concerned about heat soak response times) to overdrive the Peltier on a limited duty cycle or reduce its current draw by sensing CPU activity or instantaneous heat generation. A fast acting thermistor might answer that need. Have I postulated anything stupid here guys?

Interesting question?Thank you.

Lonnie

Hi Lonnie,

What you said sounds pretty good. I think that this will entail water cooling the cpu and video card(s) with a nice system. Maybe use the peltier coolers to cool the water that circulates, after it passes through the radiator.

The main reason I want to do this pc cooling project, is because I want to make it really quiet. Water cooling done right is amazing, it cools really well, and is silent.

I'm starting to think that active cooling a pc efficiently wouldn't be possible. The peltier that would be required to move 300 watts of energy would have to be at least 400 watts, because in reality pelts are only about 75% efficient. And in todays day and age, we should be thinking about using less energy. I mean I don't want to see many more winter nights that are 50 degrees! I've seen summer nights colder than that even in my lifetime!

But I gotta use those pelts somehow! I just have to! Something that is so cool about them is that I would have them, and no one else would. haha, to bad they are stupid and inefficient. But, sealing off the computer from the outside has it's merits. It wouldn't have any dust problems at all.

Maybe I should just forget about using pelts at all? Gotta use that powersupply for something... maybe that Pioneer 400 watt 4 channel car audio amp with 0.008% distortion to use with my new speakers I made... yeah, that's it... I think I'm gonna need bigger than 10 gauge wires...

Thanks for the input everyone

-Nick

nickjd

One last comment--and a politically incorrect one at that. Don't get too hung up on the efficiency numbers. They don't really mean what lots of people think they mean. your 75% is really pretty good--and how was it calculated? Compared to many devices (like IC engines for instance) the Peltier isn't too bad. If you look at the total heat energy in a gallon of oil, an engine uses only a few percent. If you look at the useable, extractable energy between ambient and meltdown, it is considerably better.

If you look at hydro electric it looks really good. When you look at the percentage of the sun's total radiation that strikes the earth, the part of that that evaporates water, the part that is captured behind dams and the part that goes through the turbine, the efficiency of the system makes you wonder what the Creator was thinking about. Maybe He flunked Thermodynamics.

So far as the earth boiling over because you choose a 75% efficient device and waste a hundred watts--wait a minute, turn down you thermostat and let the "waste" energy heat your house. Use your head and don't believe very much of what you hear from Al Gore et al. I better stop before the Thought Police come after me.

Lonnie

For these peltiers at least, when I say 75% efficient, a 100 watt pelt could move 75 watts of heat, but that can change at different temperatures. I'm not sure how it is calculated for compressor type refrigeration, where a 100 watt compressor can move 160 watts of energy. Now they don't call it 160% efficient, that's impossible. So yes, that is a good question, and that should be looked up.

You are right though, using an extra few hundred watts of energy isn't all that much. BUT, I actually calculated how much it costs to keep my current computer running 24/7, and it would be like $20 a month. I took that estimate from NW Ohio, where we get power from that poorly run Davis Besse Nuke plant. They really gouge us. We pay something between 9-14 cents per KWh. Correct me if I'm wrong, but that's how much people in california pay!

Only 9 to 14 cents a unit!!!!!

Is that all Nick?

Here in the UK it twice that price, well, about 9 to 12 pence a unit!!!

I wonder if we can lay a cable across the pond and hook up to your supplier?

John.

In Sydney, Australia, we have two rates for domestic electricity. For normal peak demand use we pay around AU$0-13 a KwHr (US$0-10 UK£0-05.2) and an of peak rate that is used for heating water etc at AU$0-04 a KwHr (US$0-03 UK UK£0-01.6).

On the mainland nearly all electricity is generated by coal fired power stations with a little from hydro gas and a tiny amount of wind. Tasmania on the other hand is mostly hydro. With the cost of electricity being so low and coal being so incredibly abundant there is considerable opposition to change.

Well, I looked up the costs per kwh, and it's actually 13 cents for commercial customers in my home town area. I couldn't find residential, but I would think it would be more. I would have to call home to get the most recent price (because I'm at school now), but I think that we pay a good $150-200 per month, (so around 75-100 pounds?) and in the summer it is usually more than 200 bucks. The base cost per KWh isn't too bad, but then there's taxes per unit, and a whole load of base fees. We use less power than the average household in the area too, so it's not like we keep the Air conditioning at refrigerator levels in the summer either. Also, the average rate for ohio is around 8-9 cents... So how much do you pay over there? If you would like, I could find more accurate information on how much we pay at home.

You probably never heard about the Davis Besse Nuclear Power plant that almost blew up (I doubt that information like that travels over seas). It is so poorly managed (by an evil company called "Toledo Edison"), that acid ate through 10 inches of carbon steel shielding (without being noticed somehow!!!!), and almost had a reactor breach. If it wasn't for the 1/4" stainless plate outer shell, we would all have a little radiation problem. It's like, "Hey, that's strange!!! I wonder why there's a bulge on the side of the structure?!?!" I don't know that much about reactors, but all I know is that acid ate through everything except the outer stainless shell.

Hey, if you help me build a microwave transmitter to reflect off a shiny satellite, I'm up for it... that would more fun than a long cord...

"You probably never heard about the Davis Besse Nuclear Power plant that almost blew up (I doubt that information like that travels over seas). It is so poorly managed (by an evil company called "Toledo Edison"), that acid ate through 10 inches of carbon steel shielding (without being noticed somehow!!!!), and almost had a reactor breach."

That's the problem with things U²³⁵ fission reactors and for that matter any sort of industry that handles exceedingly dangerous materials. It only takes one short sighted, corner cutting, greed oriented, bean counter driven, company to stuff it for everybody. Combine that with the grossly inept, feebly trained, poorly paid, inadequately qualified, operators that the aforementioned managers love to hire and you have the recipe for a disaster of catastrophic proportions.

Boy, I wish I only paid $.14/KWh instead the $.20 I pay!

It appears that the real problem here is the direction in which to
direct the 'dorkdom`.

While peltiers are 'way cool` in more ways than one, the simple fact
is that ANY powered cooling mode is an overall energy negative.

Your location suggests that for the better part of the time, exterior air will
be cooler than the internal enviornment. A simple filtered 'dryer duct` system
driven by a low powered biscuit fan is your greenest option. (You can elect to use
indoor enviornmental air in summer day conditions. - Do watch for condensation in
winter however.)

Isn't optimal efficiency in the given condition the 'dorkiest` thing after all?

The fuss about cooling microprocessors amazes me. I can remember back, in the good old days, working on a really powerful 10 MIPS system that had the following power supplies

CPU 5 V @ 200 A and 2.2 V @ 150 A

Memory 5 V @ 120 A and ±12V @ 50 A

IO Rack A 5 V @ 120 A and ±12V @ 50 A

IO Rack B 5 V @ 120 A and ±12V @ 50 A

The whole think was cooled by two 2 Kw (2.5 Hp) blowers in the base of the machine that provided the obligatory tornado that was required to stop it melting..

One day a machine that was under test overnight was found as a burnt out shell. Investigation revealed that one of the connectors on the +5V rail wasn't tightened properly and the heat build up in the connector set fire to the back plane. The blower assisted fire then spread through the entire system helped along by the remaining power supplies that had now turned into carbon arc lights. Well it wasn't quiet that bad and I have embroider the story a little but the loose connector did destroy the CPU, memory and associated power supplies.

The whole thing was controlled by a micro processor that sequenced the power up and down of the power supplies and fans. It was important that you never just killed the power as the residual heat would damage the CPU. You might get away with killing the power once or twice but you were tempting fate and sooner or later, usually when it was most critical, you would end up with an unstable system.

Ah the good old day, I'm glad there in the past and I don't work on monsters like that any more. I know this isn't what we are talking about but I thought it worth mentioning to give some sort of perspective. Mind you cooling a single chip that pulls 1% of the sort of power this monster did can be extremely difficult as the volume of material that is consuming the power is so much smaller and therefore prone to overheating in a much shorter space of time.

Hi to all,

Our company produces an embedded system with inside:

- PC

- Power Supply Unit

- Video Controller

- LCD (32" to 55")

all packed in an IP55, armored box, used in harsh environement. The excessive warmth produced by the LCD inverter, the PC and the Power Supply Unit is a problem, expecially when the ambient temperature is about 45 degree celsius (113 °F).

The only cost effective solution, until now, is a 5x 12" fans inside the box that blow air against an array of 3 heatsinks, placed between the inside and the outside the box. Each heatsink then has another 12" fan that blow ambient air against it (to increase the difference of temperature and then increase the warmth excange).

This sistem, luckily, works well until the LCD dimension is taken under 42" and the PC is not too performant.

I'm tryng to find another cooling solution that maybe isn't too expensive and is more effective to improve PC performance and increase LCD dimension.

I thought to search a thing similar to an air conditioning system inside the box, that throw the warmth outside.

Symianth, have you looked into using heat pipes through the enclosure?

They would keep the enclosure sealed but would be extremely efficient in transfering heat out of the enclosure. Only problem is that they are expensive components.

John.

I was thinking about using heat pipes some how, but I wouldn't know how to make them effectively, or even getting the fluid needed to make them work. The ones that I hear about use some kind of copper tubing, and are filled with a fluid that somehow moves heat better than a solid copper rod. As far as I know, it's more than just a metal rod. Actually, if anyone knows how to make a good heat pipe, please tell!

Symianth, that must be one big box having all those 12" fans... what is this for? It sounds interesting.

I already thought about heat pipes, but are expensive and the principle il similar to the water cooling, the difference lie in the transport of the warmth from the hot side towards the cool side (don't require pump). This mean that there must be some contact between the hot side of the heat pipe (for example an heatsink) and the hot surfaces to be cooled.

In this design is quite difficult to do that because hot surfaces are extended and placed all over the chassis. Immagine a big LCD module with a PC and PSU attached at the rear of the LCD (in positions that change from one product to another). You have to cool the big surface inverters of the LCD (think about 1/7 of surface at the left and 1/7 of surface at the right of the panel, about 610 cm² ), the PC processor (and maybe the GPU) and the PSU. We are talking of about 240 W (divided by PSU efficiency) of power absorbed from 42" model till to 370 W absorbed from 55" model.

Is a lot of warmth. And Immagine that all this is packed in an IP55 armoured box (not even a little hole), and sometimes this is exposed under the hot summer sun.

When the temperature raise above 60 °C you loose the LCD image (nematic cristals depends a lot from temperature). When you open a chassis in summer you can feel the sensation of entering in a oven.

We are lucky that the mayority of the systems works quite well (they are at the limit). An increase of LCD or PC consumption will lead to failure.

>Symianth, that must be one big box having all those 12" fans... what is this for? It sounds interesting.

Yes, but not so exciting. Take a LCD, attach at his rear a PC, a video controller and a PSU, and enclose all in a armoured, quite ugly, IP55 box. You gain an ugly expensive (you have to feed the fat cat) multimedia (HD is a utopy) LCD tank.

[quote]i took off the side panel on my PC put an unused bathroom fan next to the open pc case then cut out cardboard to fit around the fan and cover the case and sealed it with duct tape. It sucked about 1 cubic foot of air in through the computer and out the fan a second. The only problem was that after a while it was recylcing the same old heated air and my room would get hot.[/quote]

I do a similar thing. I have a bathroom fan (100 CFM) mounted to a 16"x25" sheet of 1/4" thick plywood. A 1"x1" frame goes around the outside of the plywood sheet, and there's a little bit of strapping (even a paint mixing stick) screwed to the 1x1. What's it all for?

The strapping holds a 16x25" MERV 7 pleated paper furnace filter centered on the 1x1 frame, which provides massive space between the filter and the plywood backing for the 100 CFM bathroom fan to draw. This is my supply of filtered air to the computers, and it massively exceeds the draw of the fans in two computers - ie. the computers are obviously under pressure (smoke test), meaning I haven't had to clean out cat hair in over a year. Furthermore, the filter has been in place for well over a year now and barely has a mark on it (why would it? Pleated paper filters generally last over 3 months in a furnace).

The fan blows into a tee, which feeds cut up soup cans riveted to the front of the two computers. The computers then exhaust through soup cans (rear, power supply) attached to vinyl ducting blowing outside (summer) or into my heating system's cold air returns (winter).

One drawback: the noise of the bathroom fan. My workstation and server sit together on one side of a wall, the keyboard and monitor for my workstation live on the other side. Problem limited. You could also mount the fan/filter assembly some distance away from the computers, using 4" vinyl ducting.

Another thing I've tried is an old fridge. I have a 1950s fridge, and before I restored it, I simply used it as my computer closet. One small hole in the back (make sure you don't hit a refrigerant tube!) for cables, and you have a nearly silent computer system. I had the thermostat set as high as it would go, and the fridge would only start up at about 15C or so. It barely ran most of the time, but if I did a few hours of number crunching, the compressor might run more than a few seconds. Alas, the now modern-insulated and properly grounded 1953 QuikFrez has been retired to her original task in the kitchen, where she glistens beneath fresh high-gloss automotive paint.

www.glowingplate.com