158w pelt under ek-supreme with 360rad

[MadDias]

hi,
i just ordered a cheap 158w peltier on ebay.
i´m going to put the cold side directly on my ph2 940be and the ek supreme on top of it.
i don´t want to go much below ambient temps (25-35°C in summer) so i decided to go with a rather low wattage tec.
as my 850w psu is only loaded with 440w at full load i guess there will no problem with hooking up the tec to my psu.
what i´m worried about is the waterloop. i´ve got all blocks (cpu, gpu (4870x2),mosfets,nb, sb) in one loop cooled by a 360mm rad.
how much heat will this 158w tec produce? i don´t want boiling water in my loop..

[flak-spammer]

It is highly likely that the ebay seller listed the Pmax as in I*v instead of the Qmax I'd say that might move around 100 watts of heat so it's doubtful that it is powerful enough to cool your CPU. a 226 Qmax TEC would have been the lowest that I would have used. Also I would not recommend all of that in one loop, TEC's generally generate a lot of heat many produce over 100 watts of heat plus all the heat they have to move from the CPU so you are looking at the TEC producing minimum 300 watts of heat more likely 400 or 500 watts of heat. So you'd probably want to separate the CPU and have it in it's own loop. That's about as much help as I can give.

[zipdogso]

i just ordered a cheap 158w peltier on ebay.
i´m going to put the cold side directly on my ph2 940be and the ek supreme on top of it.

Oh dear...
Your ph 2 has a TDP of 125w your 158w TEC will only pump about 70w with good watercooling on the hotside.
Under load for a period of time may cause your ph2 to overheat.

i don´t want to go much below ambient temps (25-35°C in summer) so i decided to go with a rather low wattage tec.

No this is the wrong approach to the problem ideally you would use a large TEC undervolted and controlled with a controller relative to the ambient temp.

TEC's vary in temp. a lot and very fast one minute it can -10ºC and the next 5ºC it is possible but not easy to control them over a limited temp range. Even the lowest rated TEC with only a small load will definitely go sub ambient and in many cases subzero you will need a controller to achieve what you plan (but NOT with this TEC !)

as my 850w psu is only loaded with 440w at full load i guess there will no problem with hooking up the tec to my psu.

Think again...even at 12v the TEC will draw more current than is safe to use with single wires from your PSU. The single wires and molex are rated at 8amps it is wise NOT to use more than 7amps. To use it in your PC with the PSU you will need to use two yellow and 2 black wires. The wires you use must be traceable directly back to the PSU body with no other components on them at all. Depending on how many wires you have this is usually impossible in a well configured PC. So you need two yellow and two black wires traceable back to the PSU body, with no other components on the wires. You cut off all the plugs on all the wires and solder the 2 black wires together and then solder the 2 yellow wires together and attach the TEC to these....and no you can't use molex connectors. And of course ...unles you want a high speed run to the nearest hospital you will UNPLUG the PC from the wall socket before EVEN THINKING of doing this.
Still want to use your PSU ?
NO....the best bet is to get an auxilliary power supply....and a relay so it turns on with your computer.

what i´m worried about is the waterloop. i´ve got all blocks (cpu, gpu (4870x2),mosfets,nb, sb) in one loop cooled by a 360mm rad.
how much heat will this 158w tec produce? i don´t want boiling water in my loop..

I really wouldn't do what you plan...keep the TEC in it's own loop TEC's generate quite a bit of heat internally even the small ones and the 158w unit you mention will with a 70w pump give off about 160-170w because it is being used in a high power situation. ( 12v when rated at 15.6v.)

[MadDias]

Think again...even at 12v the TEC will draw more current than is safe to use with single wires from your PSU. The single wires and molex are rated at 8amps it is wise NOT to use more than 7amps. To use it in your PC with the PSU you will need to use two yellow and 2 black wires. The wires you use must be traceable directly back to the PSU body with no other components on them at all. Depending on how many wires you have this is usually impossible in a well configured PC. So you need two yellow and two black wires traceable back to the PSU body, with no other components on the wires. You cut off all the plugs on all the wires and solder the 2 black wires together and then solder the 2 yellow wires together and attach the TEC to these....and no you can't use molex connectors. And of course ...unles you want a high speed run to the nearest hospital you will UNPLUG the PC from the wall socket before EVEN THINKING of doing this.
Still want to use your PSU ?
NO....the best bet is to get an auxilliary power supply....and a relay so it turns on with your computer.

my psu has 6 12v rails, each rated at 18A. so i thought i could use one rail to feed the tec.
of course i´ll unplug the psu from the wall
i´m an electrician and i´ve been to the hospital for 24h ekg surveillance because of a 230v/ac shock at work.
looking at the datasheet of the tec1-12710 and seeing the max heat output of 50°C also made me think, if this thing is even able to cool my cpu down a little. my cpu reaches 56°C under full load at 1.55v.
but on the other side, i see alot of those air-tec cpu coolers that are using much lower watted tecs. what´s up with that?

[zipdogso]

my psu has 6 12v rails, each rated at 18A. so i thought i could use one rail to feed the tec.

Well if your an electrician as you say you should know about the ratings of wires at least....and plastic fittings (possibly.) Irrespective of the current rating of the rails the individual wires and all molex plugs are only rated at 8 amps. the more recent PCI plugs have a slightly higher rating. Think about it....there is nothing in a PC with a high current draw.

looking at the datasheet of the tec1-12710 and seeing the max heat output of 50°C

Where did you see this ? I have never seen any GENUINE specs list heat output in this way.
There are two things you could of seen:- See attached spec for 12710
1.)
The 69ºC and this figure is used for the vast majority of single stage TEC's it might vary by at most + or - 2ºC. This is the maximum allowable temperature between the hot and cold sides. It has no bearing on the heat output.
2.)
The maximum heat pump is always in watts and It is often quoted at a set temp. usually this 25 or 27ºC sometimes this is 50ºC. All it means is when the hotside is at 50ºC the qcmax is ??? (quoted in watts.)
The qcmax for 12710 at 27ºC is 89w. This is max heat pump through the unit in ideal conditions and is basically unobtainable, due the inefficiencies of heat transfer like I said with good water cooling on hot hotside it would be reasonable to expect somewhere around a 70w heat pump.

my cpu reaches 56°C under full load at 1.55v.

The ph2 produces 125w at max load and yeah...who gets a 4 core to max load ? the TEC is still underpowered for direct die attachment to the CPU. Your CPU WILL run very hot and possibly overheat. You certainly wont get any overclock. Indeed if the coldside of the TEC gets too hot the heat will transfer to the hotside and set up a heating cycle which if allowed to continue will burn it out.

EDIT think about it seriously...the TEC will only pass about 70w the remaining heat will stay in the CPU/CPU socket as the seconds tick by this heat will be compounded by more heat and the CPU will heat up. The watercooling you have attached to the hotside will not have any effect on the CPU it will only cool the hotside of the TEC which will be giving off about 160w as I said earlier. Incidently when using TEC direct die you should have a temp. control /alarm program in case the TEC fails.

but on the other side, i see alot of those air-tec cpu coolers that are using much lower watted tecs. what´s up with that?

The air tec cpu coolers that you are referring to are like the Coolermaster v10 ...yes ?
They have temp. regulation circuits that either adjust the power of the TEC as necessary or only turn the TEC on when needed. The bulk of the cooling is done by the heat pipes cooled by the attached fan. There is only need for low powered TEC's and secondly only a low powered TEC can be connected by molex to the PC. Even the massive boreas which has 12 TEC's has to have the TEC's undervolted and wired in such a circuit that the current draw is below the safe level for molex connection...and if your the electrician you say you are you would know how they do it !! since it is basic simple low voltage circuits.

Incidently I am not an electrician...I trained as an electrical and electronic engineer for 3 years some 20 years ago.

Final edit regarding your power supply. It has 4 12v rails all rated at 18 amps BUT don't go thinking your free to put 18amps on each rail, your not P=I x V. So 12volts times 18amps = 216watts times 4 for the 4 rails = 864watts BUT the MAX power that can be applied to the whole supply 3v and 5v included is 680watts. The individual rail might be rated at 18amps but if you start using a couple of them they are NOT rated at 18amps each. Incidently data here is from the OCZ site for your OCZ gamexstream 700w I did'nt see the zalman till later but if you look it has similar restraints on the power loading.

[MadDias]

i was looking at thisdatasheet
i know about wire diameters and just because molex pins are only rated for 8A it doesn´t mean that they can´t take 10A. ok things might get a little hot on the contacts then, but i´ll sure won´t use a molex connector. awg18 (1mm²) schould be good for 10A. i´m used to wire 16A with 1,5mm².
i understand that, if the tec can´t take the temp of the cpu it will, after enough time, reach the temp of the hot side of the tec and something might burn out. i was just hoping that the delta tmax of 66° (coldside/hotside) would stay in every condition. meaning, that if the hot side would get to 76°C for example, the cold side would be something like 10°C.

[zipdogso]

i was looking at thisdatasheet

Well the data sheet is fine. The 50ºC you saw was simply the rating of the TEC with a hotside temp of 50ºC. The problem with TEC's is everything except the physical dimensions is variable dependent on other variables. So even the temp you operate it at will affect things. The data sheet you saw varies slightly to mine (It is rated at 27ºC.) but in the main all figures are correct.

i understand that, if the tec can´t take the temp of the cpu it will, after enough time, reach the temp of the hot side of the tec and something might burn out

Not quite the heat build up will probably damage the cpu sooner than the water cooling of the TEC will allow the TEC to burn out.

i was just hoping that the delta tmax of 66° (coldside/hotside) would stay in every condition. meaning, that if the hot side would get to 76°C for example, the cold side would be something like 10°C.

Yes you are correct BUT this figure is a maximum... the actual difference is affected by the hotside cooling. The 66ºC is not a figure that is maintained it is a figure you must not exceed. That is why you need to keep the hotside cooled as much as possible. Good water cooling with quality parts & TIM and sufficient pressure on the TEC should get a temp. difference of 10-20ºC. If you were applying only 50% Imax the majority of 127 junction TEC's (possibly all TEC's.) would not even operate with a temp difference of 66ºC. This is shown on performance charts but of course in real life you would simply never get there.

If you think about it a TEC is only 3mm thick on average so a difference of 66º over 3mm is pretty impressive. If the difference is any greater at any time the the heat starts changing sides and a heating cycle starts up and both sides of the TEC just get hotter and hotter and eventually melt the solder contacts inside the unit.

Finally
The bottom line to your problem is the fact that the coldside temp will swing wildly up and down dependent on the load of the CPU and regulation of the temp. to a small range to avoid going under the dew point is almost impossible without some form of controller based on the ambient temp. A large TEC undervolted to achieve the heat pump your looking for has a degree of built in temp regulation (due to the low current flow.) so it is easier to control.

[Ultrasonic2]

The 69ºC and this figure is used for the vast majority of single stage TEC's it might vary by at most + or - 2ºC. This is the maximum allowable temperature between the hot and cold sides. It has no bearing on the heat output.

It is not the maximum allowable temp difference. It is the max achievable temp difference at the rated hot side temp with no load applied
If you increase the hot side temp the Delta will increase also but not enough to make up for the increase in hot side temp

The major factors affecting Temp delta are

Applied voltage. The lower the input voltage the lower the delta (though its not linier)

Load applied to the cold side. The Max delta is at the rated hot side temp and it assumes there is no heat being applied to the cold side.
If you have a 100Qmax TEC and you apply 100 watts to the cold side the delta will be 0 (assuming you keep the hot side at the rated temp)

Hot side temp. If you increase the hot side temp the delta also increases (So does Qmax for that matter)

[zipdogso]

[I]

It is not the maximum allowable temp difference. It is the max achievable temp difference at the rated hot side temp with no load applied

Yeah thanks Ultra...

[zipdogso]

Bottomline...your 158w won't cut it, you need a bigger TEC.

You need the hotside cooled by a separate loop to your other stuff.

You will need a controller to avoid going subambient or you can just insulate- loads of it.

As your going to use better wiring and your an electrician I see no problem with making your own wire for your modular zalman, so long as you are within loading limits check the label/specs carefully.

Ideally your TEC needs a pressure of 150-300 psi to ensure efficient heat transfer. Your CPU only needs and most cpu heatsinks only use around 75psi.
Ideally you would use a coldplate (copper 3mm thick.) and clamp the TEC between this and your waterblock. This of course is assuming your waterblock can take it !! then attach the assembly to the TEC.

You are advised to get a realtemp/coretemp program to allow system shutdown if the TEC fails.

That's about the gist of it... I will need about 10 whole threads to get to the detailed stuff....unfortunately using a TEC is not just a case of poking one in between the block and the CPU.

[Ultrasonic2]

Bottomline...your 158w won't cut it, you need a bigger TEC.


unfortunately using a TEC is not just a case of poking one in between the block and the CPU.

yip right on