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Questions on TEC water cooling

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September 9, 2007 6:19:27 AM

I'm planning to use a pair of 245W TECs to chill water and then pipe that water to my CPU, my HDDs, and my NB (and maybe my RAM later on).
I have a few questions:
1st of all, my original plan was to do:
hot stuff -> radiator -> pump -> res -> chiller
however, it would give me more options with part locations if I could do:
hot stuff -> pump -> radiator -> res -> chiller
Would that put too much stress on the pump? Does it need water fresh from the radiator?

2nd any tips on how to insulate blocks against the dreaded condensation would be great. What is this dielectric grease for?

3rd is it really true that condensation will form on my water tubing? How do I prevent this? Do I need to insulate the tubing itself?

4th does anyone know how to control a TEC with the PWM signal from a fan header? The net is full of ideas for PWM to motor control, but a TEC is not a motor.

*sigh* I wish I'd gotten better results with air chilling. It would have made things so much easier to have the computer breathe through a TEC-chilled radiator:( 

-M4P

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September 9, 2007 6:43:09 AM

I've been involved with TEC cooling for about 4 years now and I would be lying if I said that what you are considering, I haven't wondered about myself. It is, basically, a variant on running two TECs in a cooling loop with a multitude of ways to approach how to deal with the heat.

Which brings to mind my first question - just how do you plan to deal with the heat from thw two modules? I will assume that you've designed this TEC cooling apparatus but please do explain it. Swiftech has, in th epast, developed their own chiller which was a pair of their 226 moduleson both sides of a waterblock. It was part of a cooling loop that handled normal computer parts. However, it was cooled by two independent loops itself so you can see the involvement.

Insulating waterblocks isn't as big a deal as you might think - especially since you will not be dealing with TEC waterblocks on the various components. Oh, you'll still need to seal them with neorprene but it's a rather easy thing to do. The dielectric grease is to seal the area in and around the CPU socket to prevent any condensation from forming. Yes, it does come in contact with the CPU in the socket.

In the case of the Swiftech chiller, it wasn't the insulation of the various waterblocks that really proved tasking but they had to insulate the tubing with foam to prevent condensation from forming because you'll be running a chilled liquid through a case that has other sources of heat.

September 9, 2007 7:14:16 AM

Well, let me answer your first question - this is how the system works, or at least how it was planned. The chiller is two Inovatek (sp?) HDD water blocks sandwitched together with the TECs between them. I'm still working on an insulator to fill the remaining space between the HDD blocks (TEC's don't cover entire surface, so I need somethign 3 mils thick to cover the rest of the space).
This was my plan:
Rad -> pump -> res -> T-splitter
Half of the water from the T-splitter goes through the cold side of the block and thence to the parts that need cooling. The other half goes to the hot side of the block and then into a T section that combines it with water returning from the cooled components. The combined flow then returns to the radiator.
I have a BIGASS radiator (this is a technical term) that takes 4 120mm fans, so I should be ok for heat dissipation.

Do I still need the dielectic grease if I'm not putting a TEC directly over the CPU? If so, does the grease just go around the CPU, or does it go into the socket and then the CPU goes on top. I'm guessign it's the first answer, since the grease is an insulator XD

I'm using Tygon 1/2" ID tubing (except for the Koolance HDD block, which uses 1/4" ID tubing). Any suggestions as to what to use to insulate it?

I'm actually starting to think I might be happier if I cut out the chiller, stuck a Swiftech TEC block on my CPU, and just cooled the rest of my system down to ambient. After all, as my friend pointed out, unless I am computing in *HELL*, ambient is enough to make any component happy.

BTW, your little icon "Goa'uld inside" cracks me up.

-M4P
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September 9, 2007 8:36:16 AM

lol.....

While I admire your "enthusiasm" about the subject, I think your friend may hace something there. Now, that was not meant to discourage you but to let you know that your project will require considerable involvement and, unless it is purely a labor of love, it may be more than you both realize and want to get into.

That being said....

The dielectric grease goes dirently into the socket. It is an insulator against moisture but it has electric properties that allow the CPU to operate normally. While, off the top of my head, I am not certain as to what performance reults your idea may achieve, I feel sure that it will, initially, be capable of below ambient temperatures of considerable depth. Now, some of that will be offset by the collective heat generated by the components. Remember, TEC, while really nice, are terribly inefficient.

For a time I ran two 226watt TECs in my cooling loop - one, a Swiftech CPU waterblocka nd the other, a custom 226 block for my 7900 GTX (yeah, this was last year). I had to have a minimum of a dual 120mm rad for each block to deal with the heat. so, I had two external dual 120mm rads, one for the GPU TEC and one for the CPU TEC. They would both get a bit warm still. This is to give you an idea what kind of heat you will be dealing with. For two 245watt TECs (which, I am certain are the same as mine but with the voltage upped a bit) you will need a pretty sizable cooling solution for the hotside (a triple or quad or 2 dual 120mm rads).

I'll tell you, I ran two independent loops in my computer, whose only common element was that they both ran into each other at the reservoir. Your apparatus is going to be considerably large and it will task a lone pump. You might consider a second pump and a second loop here.

I have to agree with your friend, though. The chiller is a nice idea but is terribly involved. Swiftechs new 6500-T CPU TEC waterblock is pretty nice - I am using one and with my C2D 6600 running at 3.0 my reading is still 0 degrees celsius.

PS. What can I say, I'm a Stargate fan....
September 9, 2007 11:26:55 PM

Thanks for the info. After much thought, I've decided to shelve the dual-pelt block for the time being.
Since you have a Swiftech TEC block similar to the one I am planning to use, what did you have to do to prevent condensation? Was the gasket provided with the unit enough, or did you have to slap neoprene on the back and dielectric grease in the socket?

-M4P
September 10, 2007 2:42:52 AM

What you will need for condensation prevention is:

Conformal Coating -(Acrylic Gloss Coating)
Its a spray on laquer that you can either order from online stores like FrozenCPU or Sidewinder Computers or go down to a hobby store that deals in arts & crafts. (It'll be the one that contains xylene and toluene). This goes on both sides of the motherboard in about an 1 - 1 1/2 inch area around the socket. You spray this on the back of the motherboard where, you estimate, the waterblock is on the other side off. On the main part of the motherboard (front) you spray it aboutan inch to an inch and a half area around the CPU socket.

Be very careful here.

You don't want to plug up any slots, aux fan plugs, the CPU socket itself, ram slots etc. So, BEFORE you spray the main part of the motherboard you MUST use masking tape (packaging tape) and cover any and ALL areas where you fear the spray might get into (this includes volt regs).

Cover the ram slots
Cover the Aux fan plugs
Cover over the top of the CPU socket (I mean with the CPU hold down closed - the only thing that EVER goes INTO the socket is the dielectric grease)

Dielectric grease - (You can get this online at most online stores that also sell TEC blocks - FrozenCPU, Sidewinder Computers, etc.) this goes INTO the socket and in the gaps between the socket and the neoprene foam that comes with the TEC unit. Your TEC unit should come with instructions.

Neoprene - What comes with the unit is exactly what you will need. You'll put a slab of neoprene on the back AFTER you've sprayed the conformal coating and it has dried and, of course, neoprene goes around the socket itself.

That should do it....
!