Announcement

Collapse
No announcement yet.

Sub Zero chill box build.

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Sub Zero chill box build.

    Hi all,

    A couple of people have expressed an interest in seeing my recent build so I'm going to post up pics of the build in progress and some of the ideas and pitfalls.

    I was knocking ideas around for some time on how to get sub zero temps and avoid problems with condensation. I know its possible to seal the motherboard to prevent this but I would hate to find I hadn't done an adequate job and have the build die on me.

    So I came up with the idea of a sealed chamber which contains a cooling source and the main pc components being air cooled inside it. My thought process being that any moisture in the contained air would tend to condense out on the cooling source and as the pc components are not being directly cooled they would always be warmer than the surrounding air and so not attract condensation.

    I took my ideas to run by the guys at the extreme overclockers forums thinking that was probably a good place only to find they have done similar things previously and call them chillboxes....oh well...just reinvented the wheel.

    So lets crack on with the details....just to warn you...this is not a pretty build...its purely functional.

    The cooling power comes from a 12000 btu window air con unit....that's 3.5KW of cooling!

    Here she is before I took my screwdriver and hack saw to her.



    Uploaded with ImageShack.us


    This unit alone cost ?400....so this is not a cheap project.

    You have to strip it down to expose the cold radiator...correctly called the evaporator or evap for short.



    Uploaded with ImageShack.us


    I was quite lucky with this unit, there is a nice gap between the evap and the rest of the unit and the entry and exit pipes come out of the top of the evap....all makes for an easier build.

    Next is the building of the chamber, it obviously has to be insulated and absolutely crucially has to be sealed completely air tight.

    Getting it air tight is quite a task, as you have to run so many cables through the chamber wall as everything except the mobo, cpu, gpu and ram has to be outside the chamber.

    Every cable has to be individually sealed, including each cable in the 24pin atx power cable bundle otherwise air will enter between the cables.

    An addition I made to my chamber, which is unique to my chillbox build, but I think quite important to help prevent air entry is an external expansion/contraction chamber to equalise internal and external pressures.

    We've all experienced the suction effect you get when you close and try to reopen a fridge door, well that's because the air inside has contracted with the cold and is so sucking the door closed. If that pressure difference isn't equalised then it will tend to draw moisture bearing air into the chamber through any small imperfection in the seals.

    Also if the air is at a lower pressure in the chamber that would also have an adverse affect on cooling efficiency.

    Oh almost forgot...as a belt and braces approach to combat moisture I also have 2 large pouches of desiccant in the chamber.

    My chamber is constructed out of 6mm acrylic to form the outer box and 50mm insulation board which forms the internal insulation box. Both boxes are independantly sealed and both seal via gaskets to the lid which is clamped on with webbing ratchet ties to provide a high closing pressure.

    So just from this brief description I think you can gather this takes alot of work/planning/thought and quite an expense....add another ?400 for materials cable extenders etc etc etc.

    Here's a picture of the box showing the evap and triple fan stack to the side. When the lid is on it also seals to the top of the evap and fan stack to make two chambers, one to the front and one to the back. This allows for a circular flow of air, the fans pushing air into the back chamber through the evap/rad into the front chamber where motherboard is housed.



    Uploaded with ImageShack.us

    And here it is with the mobo in place, you can also see the 2 large pouches of desiccant in the back chamber.



    Uploaded with ImageShack.us

    Here it is with the heavy duty lid on.....like I said not pretty....but functional.
    The banister rail on the top is to convert the tension in the webbing into a closing downward force on the lid rather than just tending to crush the box.



    Uploaded with ImageShack.us

    And the crucial bit...the expansion chamber....or sac actually...lol



    Uploaded with ImageShack.us

    It's a space hopper connected via a 19mm breather pipe to the chamber...lol....like I said, I'm personally not too concerned about esthetics, I needed something which was able to accommodate volume changes up to 9 liters and maintain the integrity of the sealed chamber....this was ideal even if a little silly.

    There's a few caveats I want to add for anyone considering anything similar.

    Firstly safety.....don't forget that the ac unit runs on full mains voltage, and mine has a large capacitor in the circuitry that could potentially hold charge even when powered down.....it's easy to forget when your used to dealing with low voltage pc equipment.

    Secondly... cost, the build isn't cheap, and the ac unit has a not insignificant power draw.

    Thirdly... heat pipe design heatsinks do not work with this set up...they use distilled water in the heatpipes as a working fluid/evaporant which obviously freezes and cannot move the heat as intended.

    I use a solid copper Zalman 7500cu cpu heatsink.

    My current graphics cards also have solid metal heatsinks but I can see a potential problem when I come to upgrade them as most graphics cards now use heatpipe or vapour chamber designs (which use the same principle). So if I can't think a way around that then I may be restricted in my gpu upgrade choice. Another point to note is fan design, fans must run on ball bearings not fluid bearings....the fluid freezes.

    Fourthly....cooling efficiency, I've opted to use air cooling as it's simpler and cheaper, but aircooling components often operate at load with a 40 to 50 Deg C temp delta above ambient. I still have that same temp delta but of course operating from a -30Deg C baseline.
    Other forms of cooling are more efficient and can reduce that delta considerably. I have colleagues over at the extreme overclocking forums that use similar systems but include water cooling. These require the use of alcohol/glycol/water antifreeze mixes which can attack some materials and cause leakage, this together with the fact it adds another layer of complexity and opportunity for failures is the reason I've steered away from that route at this time, but may have to go the water loop route if I can't solve the gpu heatsink problem.

    Fifth....size and noise, my systen is 3-4ft long by 2-3ft wide, the compressor on the ac unit makes a noise. I have mine in a spare room and I game using headphones so the noise is not a problem for me.

    This is still very much a work in progress for me and I'm looking at ways to make improvement.

    I'm considering using a different gas in the chamber, one that cools more efficiently than air and so reduce the temp delta. Some refrigerant gases are 5X denser than air and at the same cfm flow have, I think, the potential to cool 4X more efficiently which would greatly reduce the temp delta above ambient.....but would not solve my longer term problem of gpu cooling.

    In the longer term I'm considering something very different. I'd have two gases in the chamber. One would remain a gas at chamber temps while the other would liquify out to form a pool of liquid gas at the bottom of the chamber which the mobo would be laid flat in and submerged...this would effectively give me direct phase change cooling of the components which I could use without heatsinks and so also solve my gpu problem.
    But that is for the future as I'd have to redesign my chamber.
    Last edited by technogiant; 10-20-2012, 04:00 AM.

  • #2
    I like the concept, it looks really well thought out, especially for the expansion chamber. Now, how are the CPU and GPU temps when maxing them out with Intel Burn Test and Furmark?
    I'm sorry Dave, I can't do that.

    Comment


    • #3
      Yes it did all take a lot of thinking out and I'm happy with the expansion chamber idea, I keep a very slight positive pressure in the sac which I believe also helps to prevent any atmospheric ingress.

      I've left my chamber sealed for over 5 weeks being used very regularly for +3hr gaming sessions and it was still completely dry. Other people with similar builds have to open the chamber and dry it out with a fan regularly...I put it down to a good solid thought out build and primarily the expansion sac.

      As regards temps.....well of course that is all relative. As an overclocker you use your improved temps to push your overclock further...which of course further increases your temps.
      So the only fair comparison of temps would be at stock settings.

      I don't have stock setting temps atm but can record those and post up later.

      I've have pushed the system as far as I can (despite my cooling system I'm a novice overclocker)....I've got my 2700k up to 5.4GHz stable in the Intel Burn Test at 1.51vcore.

      At that clock speed and voltage all the cooling overhead is used up and cpu temps are back to 60-70 Deg C....Intel Burn Test is a beast.

      I've been able to get to 5.5Ghz at 1.49vcore and although not stable with Intel burn test it is with all the gaming benchmarks and live multiplayer with BF3 which is very cpu intensive.

      I've found there to be little advantage in reality in going from 5.0Ghz to 5.5Ghz with my system in gaming scenarios so have turned the overclock back to 5.0Ghz at 1.38vcore.....but it's nice to know I've another 1/2 Ghz under the hood should I need it.

      Another advantage of active cooling is at a given clock speed your are able to get stable at a lower vcore....I doubt you will find an ambiently cooled system out there at 5.0Ghz and approaching anywhere near as low as 1.38vcore which is good for me as people are raisng concerns about cpu degradation if high vcores are used.

      If you like I'll post up some benchies and temp screenies.

      Almost forgot the gpu's......same argument applies really....I've got 2x gtx460's 2gb versions....cheapy Palit sonic models they are at 960Mhz up from the palit default clock of 700Mhz....the max I was able to get out of them before my cooling system was 820Mhz...so I've been able to more than double what I thought was already a considerable overclock.....and the temps run in the 20-30c region rather than +70c during intense gaming/gaming benchmarks.
      Last edited by technogiant; 10-20-2012, 11:10 PM.

      Comment


      • #4
        Just had sometime to do the temp testing and screenies....so here we go.

        First up Intel Burn Test (IBT) cpu on stock with turbo on hyper threading off ( this test actually runs better with hyperthreading off and produces more Gflops).



        Uploaded with ImageShack.us

        Now at 5.0GHz 1.36vcore



        Uploaded with ImageShack.us

        And at full wack 5.4GHz 1.51vcore



        Uploaded with ImageShack.us

        And as for the gpus....well her's furmark temps at default gpu settings of 700Mhz 0.987vcore



        Uploaded with ImageShack.us

        And at full wack 960MHz 1.112vcore



        Uploaded with ImageShack.us

        It's not quite stable in furmark at those settings but you can just see the temps plateau out at about 54c on gpu 1 and 40c on gpu 2......but it is game stable at those settings.

        Of course these burn tests produce much higher temps than you experience during normal use.....I'll post up some temps after rolling the "Heaven" benchmark a few times.....that will give a more realistic view of actual usage temps.
        Last edited by technogiant; 10-21-2012, 03:34 AM.

        Comment


        • #5
          Heres some screenies of heaven benchmark and BF3 multiplayer on a busy map just toi show more normal usage temps......cpu at 5.0GHz gpu's at 960MHz.

          Heaven



          Uploaded with ImageShack.us

          BF3



          Uploaded with ImageShack.us

          Comment


          • #6
            Very cool, per se.
            Have you tries IBT on Maximum?
            I'm sorry Dave, I can't do that.

            Comment


            • #7
              Thanks, yeah I'm pleased with the temps and the useable overclcock it gives me.

              I haven't tried IBT on max, tbh though the likes of IBT and furmark aren't realistic in terms of heat production compared to normal usage scenarios......they are good for ultimate stability testing but my system is stable so I don't see much point in pushing those out further.

              My sticking point atm is that I can't get it to boot at anything higher than 5.5Ghz.....the fact it can even run IBT at 5.4GHz indicates to me it should boot up to windows at least 200 -300 MHz higher and be wprime 1024m stable as its a less intense benchmark....but will not go past the bios splash screen at anything above 5.5GHz ??

              Not even by leaving the multiplier on 55 and increasing the clock from100 to 101 to give a smaller increase than going from 55 to 56 multiplier...just will not do it, shame cos I think there should be some more there.
              Last edited by technogiant; 10-21-2012, 11:56 PM.

              Comment


              • #8
                Nice build

                Comment


                • #9
                  Very interesting build, keep us posted on any updates!

                  Thank you
                  GSKILL TECH

                  Comment


                  • #10
                    Getting 5.5GHz is quite an accomplishment.
                    I'm sorry Dave, I can't do that.

                    Comment


                    • #11
                      High guys....just thought I'd link you to my latest project.
                      It's an evolution of my previous chill box build...but this time....well where do I start.

                      The chamber is basically like a huge actively cooled vapor chamber with the motherboard submerged in the bottom of the chamber in the working fluid which is liquified gas.

                      ...perked your interest?

                      Here's a youtube link to the web cam footage from inside the chamber.

                      http://www.youtube.com/watch?v=ZUVWAdSnYuw

                      So the chamber is completely sealed and made of 1.5cm alu plate as it has to withstand negative pressures of -10psi.

                      The evaporator of my 3.6kw air con unit is sealed inside the chamber and the chamber is filled with the gaseous refrigerant.

                      When you turn the ac unit on the temp drops, liquifies the vapor causing a partial vacuum which is used to draw liquified refrigerant from a pressure bottle into the chamber sump where the pc mobo becomes submerged.

                      So the mobo is submerged in liquified refrigerant....the refrigerants boiling point at normal temp and pressure is -1c but because the cold in the chamber is causing a pressure drop the liquid boiling point also drops.....in fact the liquid is in a state of equilibrium balanced right on the edge of a variable boiling point the value of which depends on the pressure/temperature of the chamber.......you can see this in the video...the liquid is in a constant bubbling state even with no load...like a witches cauldron. The lowest temp the chamber produces is about -30c.

                      The components are cooled by the liquid phase changing...this is where it's good to have the liquid on the edge of liquid/vapor equilibrium as it's always ready to boil off given a heat input.

                      I have to contain the liquid in a pressure cylinder between uses as the chamber was not designed to withstand expansive pressure...just compressive pressure.

                      So I basically reverse the filling process.....the cylinder is place in a chest freezer so causing a low pressure inside....the chamber cooling is turned off and as it warms the liquid is transferred across through a linking pipe because of the pressure differential.

                      You like.....I think this is a first.....

                      Comment

                      Working...
                      X