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Been considering a pelt for quite some time

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post #1 of 24 (permalink) Old 10-09-2015, 08:39 PM - Thread Starter
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I've been playing around with pelts for years. First one I saw was in the climate controlled seat module of a Lincoln Navigator. There was a recall on them so I amassed about 40 of them several years ago. I hooked them to heatsinks and car batteries to see how cold they would get. Put my meters on them, researched them, played with them, and melted several of them. I still have a few in the attic.

The problem was that for years I couldn't justify the cost of creating a system that could support a pelt. Last October I paid my final $225 per week child support payment and have taken care of many important things that had gone undone for too long.

Recently I finished a system that can handle a pelt. Plus I have the finances to put into the project. You may have seen my geothermal system build thread. The geothermal radiator that I built and put 35' into the ground takes the heat from a 5Ghz 8350, 2 heavily overclocked R9 290s, 2 memory modules, and the motherboard NB/SB and Vregs. It does this and maintains a max water temperature of 27c while running P95 and furmark torture test at the same time for an hour.

So I think I'm ready to throw a pelt into the mix. I only want to TEC the CPU at this point. I know Ultrasonic used to make AMD TEC blocks but they are not listed on his sales page. I dropped him a note hoping he might have one on a shelf somewhere.

I would like to put the screws to my CPU a little more. This thing is my daily driver and I keep it clocked at 5Ghz all the time. I would like to see just how high I can go with it; both for testing and for a daily driver.

There are so many of you that know this TEC math WAY better than I ever will. Could one of you make a pelt recommendation?
The PS calculator says that my CPU will draw 260w at 5.5Ghz and 1.55v. So I was thinking that this http://www.customthermoelectric.com/tecs/pdf/26311-5M31-17CW_spec_sht.pdf would probably be the one but I am uncertain.
Thanks
John

Ryzen [email protected] on a Asus C6H with a EK monoblock--Zotac Articstorm 1080ti 2010/6200-- Swiftech Dual mcp35x pumps--32Gb (4x8GB) Corsair [email protected] 16-17-17-35-T1---Custom geothermal cooling loop with a homemade 40' copper heat exchanger 35' in the ground
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post #2 of 24 (permalink) Old 10-10-2015, 06:46 PM
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With your hot CPU, a single pelt probably won't cut it so you may be looking at a dual or even quad peltier setup. You have the BIG advantage of having a gigantic buffer of nice cool water though, which will help a lot. TECs love getting cool water, and just the raw volume of coolant will go a long way towards eating load spikes.

I don't have the slightest clue on how to calculate the cooling capacity in watts of your massive geothermal loop, but you will need to be able to cool the sum of the wattage of all TECs PLUS the CPU being cooled...so if you decide on a dual TEC block with some 331w TECs you listed, your loop will have to be able to dissipate over ~900w of heat just from your CPU setup plus the 500-600 watts of your GPUs! 1.5kw of heat is quite a bit of heat smile.gif.


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post #3 of 24 (permalink) Old 10-10-2015, 06:55 PM
...and you'll FLOAT TOO!!
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How can you mention this kind of system and NOT post any pics?? biggrin.gif
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post #4 of 24 (permalink) Old 10-13-2015, 03:17 AM
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http://www.customthermoelectric.com/tecs/pdf/19911-5L31-15CQ_spec_sht.pdf 4 of these TECs at 12v would get you close to 0c on the cold side. They are 40x40mm so you'll need an ~80x80mm cold plate made out of copper to house all 4 of them right on your CPU, that needs to be about 10mm thick and should taper down from the 80mm to the size of your IHS. They'll handle 240w at a delta of about 30*c from your hotside temp, so you'd go close to zero on your cold plate/IHS, with all the thermal losses counted and stuff you'd probably end up with a real world CPU cold plate/IHS temp 20-25*c cooler than your water block is at now, maybe 25-30*c cooler if you're lucky.

The big barrier is getting the custom water block and cold plate made up in copper to suit the size of the 4 TECs. The next cost will be your PSU to power the TEC's, at 12v 4 of them will pull about 336w. Other than that you'll have to insulate your motherboard etc as you'll most likely have issues with condensation, unless you can track down a PWM dew point controller or have the wherewithal to make your own controller, can be done with an arduino or a straight up custom job like mindchill came up with, good piece of kit that was.

Or if you are prepared to risk it you could grab a couple of these http://www.ebay.com.au/itm/231704893134?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT you'd need 2 of them as you'll be pulling 28amps through the 4 tecs, maximum of 20a through each controller, so 14amps per each controller is fine and it allows you to set a temperature and it will maintain your TEC cold side temp at your set temperature, if you buy them you need to ask them to customise the temperature setpoint range from the standard 10-40*c down to about -10 to 20*c which would allow you to run your TEC's all out at 12v or as warm as 20*c if you have issues with condensation. You will need to buy a couple of NTC 10K 3950 thermistors to go with it, I bought one of these and I'm using a cable thermistor with the sensor inside a bead, I've drilled that inside my cold plate so that it feeds back the temp to the controller and the controller controls the TEC via PWM to always maintain your set point, so you'll need to put a TO-220 heatsink on the mosfet with 14amps going though it. This won't automatically keep you above the dew point, so you either need to set it at a temp which you are comfortable will always be above dew point, and it varies widely so that may not allow you to achieve the greatest temperatures as it won't be that far below your ambient temp, or you can insulate the motherboard and pick a temperature of about 5*c that you know your TEC's can maintain even at 100% CPU load and the controller will just keep your cold plate/IHS at that temp.

Make sure you do a good insulation job on the motherboard and CPU socket though. This whole setup only adds 336w to your whole loop so I'd say your water temp should remain about the same so I think you have a pretty good chance of getting your cold plate/IHS temp in that 0-10*c temp range even at 100% CPU load. Its up to you whether that result is worth the cost.

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post #5 of 24 (permalink) Old 10-17-2015, 11:56 AM - Thread Starter
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There are several Pics in my "journey to geothermal" thread. http://www.overclockers.com/forums/showthread.php/759850-Journey-to-geothermal?highlight=Geothermal

I was looking at the 331w pelt because of the high number of couplers are more efficient. Is this correct?
They also have a 400w 62mm pelt that I was considering. Would that one be enough by its self? I'm not limited to 12 volts as I have a PS that can do up to [email protected]

Ryzen [email protected] on a Asus C6H with a EK monoblock--Zotac Articstorm 1080ti 2010/6200-- Swiftech Dual mcp35x pumps--32Gb (4x8GB) Corsair [email protected] 16-17-17-35-T1---Custom geothermal cooling loop with a homemade 40' copper heat exchanger 35' in the ground
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post #6 of 24 (permalink) Old 10-17-2015, 03:19 PM - Thread Starter
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I must be doing the math wrong (no surprise there) using Ultrasonic's TEC calculator. He has the TEC module data for both the 331w TEC that I referenced in the first post and the 400w one I referenced in my last post.
For the 400w TEC I'm inputting 70% Umax(17.54v), 240 watt heat load (got that from eXtreme Power Supply calculator [email protected] ), and 30c hot side temp.
What am I doing wrong? Am I being unrealistic in some (or all) of my values?

Ryzen [email protected] on a Asus C6H with a EK monoblock--Zotac Articstorm 1080ti 2010/6200-- Swiftech Dual mcp35x pumps--32Gb (4x8GB) Corsair [email protected] 16-17-17-35-T1---Custom geothermal cooling loop with a homemade 40' copper heat exchanger 35' in the ground
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post #7 of 24 (permalink) Old 10-17-2015, 06:14 PM
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you have to explain that a bit more, which part is wrong or unexpected? your hot side temp sounds right, but what is the delta to the cold side temp? High couple count TEC's can be more efficient yes, they generally have a higher Umax and lower Imax but really it comes down to what is suitable in your situation. At 17.54v that 400w TEC is dumping a considerable amount of heat into your loop, ~333w + the ~240w from your CPU. You need to add the CPU heat load and the TEC heat load together, that is what your loop has to dissipate, so I'd imagine you may actually get lower temps with less volts applied to that TEC just becayse you may be overpowering your loop, and it may also be too much to ask of a single water block. Also I think extreme PSU calc has become very conservative, I think you could lower your estimated heat load from CPU a bit. If you CPU heatload really is up in the 200w+ range then it is going to be very difficult to handle with a single TEC direct die, you are getting into the territorty where a chiller will be far more effective, for instance 2 of those 400w TECs at 12v would be more efficient than 1 at 17.5v and would also give you a higher Qc at 30*c Dt. But you need two separate loops for a TEC chiller, one to cool the hotside of the TEC and any GPU's etc, and one for the TEC cold side CPU chiller loop.

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post #8 of 24 (permalink) Old 10-17-2015, 06:48 PM
...and you'll FLOAT TOO!!
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Quote:
Originally Posted by Thick8 View Post

There are several Pics in my "journey to geothermal" thread. http://www.overclockers.com/forums/showthread.php/759850-Journey-to-geothermal?highlight=Geothermal

I was looking at the 331w pelt because of the high number of couplers are more efficient. Is this correct?
They also have a 400w 62mm pelt that I was considering. Would that one be enough by its self? I'm not limited to 12 volts as I have a PS that can do up to [email protected]

Ah, sweet! Thanks for the link, that's a pretty interesting setup you have there.... thumb.gif
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post #9 of 24 (permalink) Old 11-03-2015, 07:51 PM - Thread Starter
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Sorry to be gone so long. Been really busy.
I guess I'm misunderstanding the concept of how this works.
If I pump 31.5 volts @ 17 amps into the 331W TEC and am able to maintain a hot side coolant temperature of 30c. With a cold side heat load of 200 watts I should be able to maintain a cold side temperature of near 0c. At least this is my understanding of what the calculator is saying but I have a feeling that my understanding may in some way be flawed.

Ryzen [email protected] on a Asus C6H with a EK monoblock--Zotac Articstorm 1080ti 2010/6200-- Swiftech Dual mcp35x pumps--32Gb (4x8GB) Corsair [email protected] 16-17-17-35-T1---Custom geothermal cooling loop with a homemade 40' copper heat exchanger 35' in the ground
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post #10 of 24 (permalink) Old 11-04-2015, 05:55 AM
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don't worry about the calculator, its good but its not necessary to evaluate a TEC that way. Here is the data sheet for the 331w TEC http://www.customthermoelectric.com/tecs/pdf/26311-5M31-17CW_spec_sht.pdf

If you look at the charts at the bottom of that it tells you everything you need to know about the TEC's Qc and power consumption ie the heat load of the TEC. So, at 100% Umax or 31.5v it'll pull about 16-17 amps and you'll have a Qc of about 165w at a 30*c delta.

So, if your geothermal cooling can keep the hot side of the TEC at 30*c then you will be able to keep a ~165w heat load at 0*c with the CPU at 100% usage, and it will be much cooler than that when the CPU is idle unless you use a controller to keep the TEC cold side at the same temperature. I've been using a neat little PID PWM controller that keeps my TEC cold side at 14*c for a while now and it is fantastic.

If your heatload is about 200w then your TEC will have a delta from hot to cold side of about 24*c, so if your hot side is 30*c your cold side will be 6*c. It's never quite as exact as this and you can probably factor in at least a few degrees higher due to thermal losses through the heat transfer from IHS>TIM>Cold plate>TIM>TEC>TIM>Water block. So I'd say you should be in the 10*c ballpark area with CPU under 100% load if your hot side can be held at 30*c. Bare in mind you now have a 200w heat load from your CPU plus the heat load from the TEC which is 31.5 x 17 = 535w, so 200w + 535w = 735w for your geothermal loop to keep at 30*c, that's a lot to ask from a passive cooling solution, especially if you have other components in the loop.

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