HELL BENT on using a peltier

Black_Paladin · Feb 2, 2003

Hello,

Normally I make long posts but this time I'll cut to the chase:

I have posted several posts on overclockers.com before, asking some info about peltiers. I couldn't get much information so now I am posting here on Bigg's advice.

I would like to use a peltier with my EXOS water cooling kit.

Will ANY kind of peltier work for me?

I have an about 20C difference between my water temps and my CPU load temps so I am looking for a peltier to bridge this gap.

NOT looking for sub-zero or even sub ambient CPU temps.

PLEASE. and PLEASE don't just say "no, it won't work" but provide a reason why. Thanks!

Penguin4x4 · Feb 2, 2003

Black_Paladin said:
Hello,
I would like to use a peltier with my EXOS water cooling kit.

Will ANY kind of peltier work for me?

I have an about 20C difference between my water temps and my CPU load temps so I am looking for a peltier to bridge this gap.

NOT looking for sub-zero or even sub ambient CPU temps.

PLEASE. and PLEASE don't just say "no, it won't work" but provide a reason why. Thanks!

*grabs calculator*

*does franitc caluculations with said calculator*

...

Well, seeing as you are running @ 87W idle, 116W load, I would say that it is indeed impossible. First you need to take into consideration peltier sizing, which in your case you would need at least a 232W peltier(highest one I have seen is 226W). Secondly the Exos is not that good of a watercooling solution to begin with, and with the extra thermal watts needed to dissipate the heat from the peltier the radiator would overload, causing higher temps than with no peltier at all.

Black_Paladin · Feb 2, 2003

Well, seeing as you are running @ 87W idle, 116W load, I would say that it is indeed impossible. First you need to take into consideration peltier sizing, which in your case you would need at least a 232W peltier

OK, so what happens if I used anything less than a 232W peltier than? I read the peltier sizing article before posting here and it says:

"If you are thinking of using a peltier and if the peltier is less than or equal to your overclocking target, the best possible cooling you can expect is to keep the CPU at ambient temp".

This would be great for me! My CPU temps are way over ambient temps right now. My CPU temps at ambient sounds like a dream.
So then WHY the NECESSITY to DOUBLE the watts??? I just don't get it. If I used a 150W peltier there will something like a 50W overhead and then will my computer explode??

Penguin4x4 · Feb 2, 2003

What you need is at least double of what your CPU outputs. Anything less can lead to dismal results. Given that the Exos runs at 0.23 C/W and you wish to run a 150W TEC:

Delta T = (1-(116/150))*72C =16C Difference

((116 + 150) * .23 + H20 Temperature) - 16C = CPU Temp

So with 20C water you're looking at 72C core temps. The idea behind peltiers is to acheive as good as a DeltaT as possible to compensate for the added heat of the peltier.

More Linkage

gone_fishin · Feb 2, 2003

There are dual peltier maze-2 blocks which would work if you are really hell bent on the matter. Make sure the rest of the loop can handle all the heat removal, I'm not familiar with an EXOS setup.

Black_Paladin · Feb 2, 2003

There are dual peltier maze-2 blocks which would work if you are really hell bent on the matter.

*Drool*

Yes, hell bent I am.

The problem here seems to be the fact that I need something really powerful to remove the heat of the peltier. This is why I was looking at less powerful watt peltiers.

Also, Sisoft sandra shows my CPU watts as 96W so maybe it's not as high as Penguin calculated??

I don't want to give up on this just yet.

Penguin4x4 · Feb 2, 2003

Black_Paladin said:
Also, Sisoft sandra shows my CPU watts as 96W so maybe it's not as high as Penguin calculated??

Looking at electrical specifications for the Pentium 4, we see a general trend of about 1 thermal watt increase per 100MHz overclock; 28-16=12W added to the maximum thermal output(M.T.O.) of the processor. A P4 1.6@Stock runs 47W idle, 63W load. With it running@2800 stock vcore, M.T.O. increases to 75W

[(Actual vcore/Stock vcore)^2] * Maximum thermal output of the proccesor

So at 1.83V you are looking at 112W, so yes I did rush those calculations a bit. Sorry,

. 226W with a good waterblock would be fine in this instance, and you will need to upgrade the radiator to compensate for the TEC.

Bigg · Feb 2, 2003

Penguin4x4 said:
What you need is at least double of what your CPU outputs. Anything less can lead to dismal results. Given that the Exos runs at 0.23 C/W and you wish to run a 150W TEC:

Delta T = (1-(116/150))*72C =16C Difference

((116 + 150) * .23 + H20 Temperature) - 16C = CPU Temp

So with 20C water you're looking at 72C core temps. The idea behind peltiers is to acheive as good as a DeltaT as possible to compensate for the added heat of the peltier.More Linkage

thanx dude, thats what i've n=been tellin him since friday night about tecs. look at his thread over in the extreme cooling area, and u'll see that most of the conversation has been between him, and myself. i told him to put it in a minifridge, but he says its too much work, and not lanable. look at the thread for more info.

Black_Paladin · Feb 2, 2003

So at 1.83V you are looking at 112W, so yes I did rush those calculations a bit. Sorry,

Well, actually you were off only by 4W's so I would say you were right on target. I am happy that you now say a TEC would work though.

For changing the radiator, I'll do it if I can fit the new radiator into the EXOS. Wonder what size radiator the EXOS has. I'll have to take a look.

Penguin4x4 · Feb 2, 2003

In the long run you'll probably have to get a completely new system becuase I'm pretty sure that the Exos's meager 12v pump and waterblock will not be able to sustain optimal temperatures. Again this is speculation, so let me think about this a bit...

Black_Paladin · Feb 2, 2003

Some more info:

My ambient temps are pretty good here. Not too high. My water temps are like 28C. If this were to COMPETELY double with a TEC, it would be 56C. Hot, yes, but not boiling. I think that would be OK, no?

I read the thread Bigg had linked in the extreme cooling forums and I'm now even more tempted to try out the Swifty 462uht.

Here's the link to the thread:

http://www.xtremesystems.org/forums/showthread.php?threadid=4476

And a quote:

It went down to 15 degree C in less than 2 minutes but the water is getting really warm so I have to stop....heehee but then again the ambient here is 30 degree C......so I guess if you have a below 20 degree C ambient, maybe this combi can still work.....

So the guy stopped since the water started getting warm but he said his ambient temps are like 30C. My ambient temps are much less and even my water temps are lower than 30C. So then this looks promising!

Also, check this out from the same thread:

Cold plate temp below zero but exos lcd only can show zero.......setup here without cpu......have to take care of condensation precaution first.

DUDE, this is without the CPU but it WORKS THEN!!! I don't understand why Bigg was saying this didn't work? He said something like they had to stop the experiment without the CPU attached because the TEC got so hot. Well, appearantly, this is not the case!!

Penguin4x4 · Feb 2, 2003

Hmmm, well the setup Hua Luo Han seems to work OK, so I say go ahead and try my friend! Later on you can the pump and heatercore, or whatever,

Be sure to tell how it went, as I am interested in the results...

Black_Paladin · Feb 2, 2003

Hmmm, well the setup Hua Luo Han seems to work OK, so I say go ahead and try my friend! Later on you can the pump and heatercore, or whatever, Be sure to tell how it went, as I am interested in the results...

DUDE, I AM REALLY EXCITED RIGHT NOW!! If this works, I'll be HAPPIER than a pig!!!!

I guess I'll be ordering one of those Swifty blocks.

Just one thing though: How hot can my water go before I would experience problems you think? I mean I obviously don't want my water boiling at 100C but would 50C be too hot for my hoses/radiator/pump? Would I be OK if my water temp didn't exceed like 50C?

The highest my water temps ever went was 35C and that was with the heater in the house turned on, my fans operation at %45, and the computer running Prime95 overnight. With my windows open, my water temps go as low as 17C idle and like 22-23C under load. Even then the CPU temps are like 40'ish.

With a peltier though, I bet that would change.

Penguin4x4 · Feb 2, 2003

Black_Paladin said:
DUDE, I AM REALLY EXCITED RIGHT NOW!! If this works, I'll be HAPPIER than a pig!!!!

I guess I'll be ordering one of those Swifty blocks.

Just one thing though: How hot can my water go before I would experience problems you think? I mean I obviously don't want my water boiling at 100C but would 50C be too hot for my hoses/radiator/pump? Would I be OK if my water temp didn't exceed like 50C?

The highest my water temps ever went was 35C and that was with the heater in the house turned on, my fans operation at %45, and the computer running Prime95 overnight. With my windows open, my water temps go as low as 17C idle and like 22-23C under load. Even then the CPU temps are like 40'ish.

Water should be about 35C, which is why I recommended the heatercore. But it should suffice until more funds are available,

Black_Paladin · Feb 2, 2003

Water should be about 35C, which is why I recommended the heatercore. But it should suffice until more funds are available,

Hehe OK, but what would you say the limit should be for the water temps until the funds are available?

Also, I would be VERY GRATEFUL if you happened to come across a heatercore that I could fit in the EXOS and tell me about it.

Black_Paladin · Feb 2, 2003

I haven't actually dissected the EXOS yet but I am willing to bet that when I take the current radiator out, I won't be able to fit something much bigger than that in there. Curious as to what size the smallest heatercore is compared to the size of the radiator in the EXOS?

Black_Paladin · Feb 2, 2003

For the hose size, since the current 462UHT has 1/2" barbs, could I use these adapters that I found on DangerDen to fit it to Exos?

http://www.dangerden.com/mall/tubing.asp

I'm referring to the 1/4" NPT, 1/2" OD adapters (whatever NPT means).

This is what Biggs had posted about the hose size of the EXOS:

1/4" ID, 3/8" OD would fit the swiftech mcw-462U, only it got discontinued for the one with 1/2" barbs the mcw-462UH. anyway the fitting could be changed. 1/4" is not a standardm but is widely used, so finding another blok shouldn't be too hard. 3/8" OD quick connects work with it or 5/16-3/8" tubing

So then would the adapters I found on DangerDen work? I mean the 1/4" NPT, 1/2" OD adapters. This is because the EXOS hose size is 1/4" and the discontinued Swifty block had 3/8" fittings and the current one has 1/2" fittings, right?

Black_Paladin · Feb 2, 2003

I found the discontinued block at SideWindercomputers.

This is what is says:

"Built-in quick connect fittings for 3/8" (OD) vinyl, poly-ethylene or copper tubing".

OK, so if I were to buy this, would I need to get any hose adapters to fit the EXOS to it?

Penguin4x4 · Feb 2, 2003

Black_Paladin said:
I found the discontinued block at SideWindercomputers.

OK, so if I were to buy this, would I need to get any hose adapters to fit the EXOS to it?

Shouldn't have to, since 3/8 OD refers to 1/4 ID tubing, so you should be safe. If water temps get to 40 I would shut her down immeadiately,

Since87 · Feb 3, 2003

Penguin4x4 said:
Given that the Exos runs at 0.23 C/W

JoeC measured the Exos's thermal resistance at 0.23 C/W on a die simulator.

What's that, 1 cm^2 surface area?

A 40mm X 40mm TEC has 16 times the surface area, and a 50mm X 50mm TEC has 25 times the surface area.

Assuming the WB itself is a substantial portion of the total thermal resistance - the Exos's thermal resistance on a TEC will be substantially lower than 0.23 C/W.

HELL BENT on using a peltier

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