CPU TEC cooler design ideas

[JaskarnSidhu]

Hello everyone

Im looking at designing a new TEC cooler for the CPU, only its going to be directly cooling the CPU, not using water as the median to transfer the heat.

My plan/idea is to design a thin copper plate with the CPU base being approx 50mm x 50mm square, ensuring to cover the CPU entirely, and the reverse side, where the TEC's are, to be approx 90mm x 90mm.

Im still deciding between using 1 large 62mm x 62mm TEC or 4 smaller 40mm x 40mm TEC's. I would get more cooling potential from the 4 40mm x 40mm TEC's, but the TEC plate would be huge, and space/size may become an issue.

The hot side of the TEC's would have a water block with copper heat pipes coming out from the top and having aluminium or copper fins. This way I can use a combination of air and water cooling to cool the hot side of the TEC's.

I am open to other idea's or suggestions so please do say something if you think you have a better way of doing something or a more efficient way.

[gdesmo]

Much more feasible with a chiller unit, aka heat exchanger using blocks on either side of the Tec's. your basic idea would work on a low tdp cpu ( below 40 watts) but will run into heat transfer problems when pushed at all. Also the outer edges of the copper plate will not be able to transfer the heat away quickly enough and will result in an earlier death of the unit. 4 x 40mm is the one that would possibly work the best with a fairly thick copper plate. Use some very high power 40's ( 250-300 watts 24 volt ) and under volt them at 12 volts to bring them into the efficient zone of 38-66 % of rated voltage. That being said a chiller unit with 2 x 62 mm 400 watt units(24 volt) would be way better and more eff..

[JaskarnSidhu]

i have a tec sandwich chiller that i had made. It has 3 blocks. 2 outter blocks that are the hot side of the TEC's and 1 center block thats the cold block.
The cold black has 8x 62mm x 62mm TEC's (4 per side of the cold block) and the hot side of the blocks have waterblocks on them to cool the hot side.

Im coming up with a wiring schematic so I can tie them in with my refrigerated water chiller and relays. That way when the water temp is below 28C the TEC's will remain off, but with a close on rise temperature switch, i can bring the TEC's online to maintain lower water temps.

The reason I thought about this other method was because of how many times heat has to transfer from the TEC's to cool the CPU. first from the TEC's to copper block, copper block to the water, water to the cpu copper block, cpu copper block to the CPU. I thought if you cut out the middle man so to speak you may better better results. 4x 40mm TEC's would probably work the best, but I dont know how effective they would be compared to a TEC water chiller or a refrigerated water chiller.

[gdesmo]

8 x 62's should be enough to freeze a 50/50 glycol mix almost solid. What tec's are they ? What are you cooling and how are you cooling your hot side ? Include some sort of drawing of your tec block assembly so I can understand completely what it is. Without any info I am just guessing at what you are trying to achieve. Include tec voltage, # of couples, and voltage parameters.

[JaskarnSidhu]

I have the 3 blocks designed and cut and sitting at home. I havent picked out the 8 TEC's yet, still have to pick those out.

I have a 1 ton refrigerated water chiller, which removes about 1300 watts of heat. My plan is to keep the water temps at 22C (that number may change a bit, but it will be around there). I currently using a 1/2 refrigerated water chiller which removes about 800 watts of heat and under full load (CPU and motherboard only) it keeps temps at about 30C. (CPU is overclocked to 4.8Ghz @ 1.48vcore).

My plan is to have the TEC chillers assist in keeping the water temps below or around 22C, under full load when I add 2 additional GPU water blocks to the loop. I will have close on rise temperature switches, so when the temps rise above 28C, it will close a first set of contacts which will send 30% power to the TEC's and engaging them until the temp drops below 22C or for a cycle of 5-7 minutes. If after that time the temps are still above 28C, it will open the first set of contacts and close a 2nd set which will send 50% power to the TEC's until the temps drop below 22C or for a cycle of 5-7 minutes. If after that time the temps are still above 28C, the 2nd set of contacts will open and a third set of contracts will close providing the TEC's with a final 75% power. This will stay on indefinitely until the temps drop below 28C.

My main source of cooling will be the refrigerated water chiller, because its the most effective use of electricity. If that water chiller is unable to maintain the set point, the first stage of TEC cooling will kick in, and then the 2nd, and then the third. Or I may only use 2 stages of TEC cooling, one at 40% and the latter at 75%. Im still working out those details.

[JaskarnSidhu]

The hot side of the TEC's will be water cooled. I have 3x 480 rads, 2x 360 rads, and 1x 240 rad. Im thinking that should be enough, but if its not, then Im planning on added 2 more 360 rads.

All rads have push/pull fans. When I get back to Edmonton I will post a picture of my TEC sandwich blocks which should give you a better idea of what im dealing with.

What will be cooled is:
i7 3960
Asus Rampage IV extreme black edition full board block
2x Evga GTX 780's

[gdesmo]

Are you putting the 2 cards in that loop as well ? If so it's a bit of a waste of power for tec's to cool that as well. Should have separate loop for the gpu's with a 360 and maybe a 240 at the most. Just use the 480's for the tec hot-side then and you can get a really good delta by just cooling the cpu with it. 2 x 400 watt tec's at 12 volts would be enough to get it to 5 degrees Celsius then. Any more and you will need 2 psu's or a single one with a Meanwell kicker psu to pickup the rest. Gotta go and hit the sack.

[JaskarnSidhu]

the temps of my water loop would get into the 40c range when i had my video cards, mobo and cpu in the same loop. Its a lot of heat to remove.
Its not just 5C of temp to drop, it can be as high as 20C of heat to be removed. 28C is just the threshold before the TEC's kick in.
For example: If my computer is idle, maybe im must browsing the Dazmode forums, not doing anything stressful for the computer, the refrigerated water chiller would be plenty so it would kick in and do its job. Then maybe i feel like doing some benching or folding, maybe some crypto-currency mining, and my cpu and GPU's all kick it into over drive and they are all at 100%. At that point my water temp at idle, which used to be around 22C, will now be rising and going above 28C. Let say it settles at 45C. So now my water temp is at 45C with my refrigerated water chilling going all out trying to cool my loop. At this point the first stage of TEC cooling would kick in and try to help bring those temps down to a point its satisfied in a given period of time. So the first stage kicks in and it brings it down maybe 7C. Thats still leaves the water temp at 38C which is well above the 28C set point. So then my 2nd stage of cooling kicks in to try to bring the temps down to the set point. Lets say the 2nd stage brings the temps from 38 down to 29C. 29C is still 1C above set point so then my third stage of cooling kicks in and brings the temps down from 29C to 20C.

Thats the goal im going for. The reason I want the cards in the same loop as the cpu and mobo is so I can maintain a specific temp of the water so all of my components get adequate cooling. The TEC sandwich block that I have measures 140mm x 140mm. I had it designed so I could use 4 62mm x 62mm TECS on each side, or i could use 9 40mm x 40 mm TEC's on each side, or anything in between.

[gdesmo]

Use the chiller just for the GPU's and the Tec's for the Cpu. Gpu's are designed to run at higher temps and still stay safe. You can then use 2 x 62 mm tec's for your cpu loop. A lot easier solution without all the complications.