Question about tecs, from a newb

[3vil_l337]

ok heres the deal, im thinking about cooling my new pc with a tec and some active water, and ive seen quite afew 200-300 watt tecs. now i dont want my proc to run super cold id be happy with room temp trufully. but i want to be able to get those temps whith large wattage outputs. SO my questions are as follows. if i have a tec. and i apply a large amout of wattage to it, the cold side will warm up and so will the hot side, but if for example im only using 120 watts out of a 320 wat pelt. and am not wanting to run in cold cold temps... can i reduce the the amount of wattage the tec uses (via droping the voltage) and get a same hot side temp with a warmer cold side temp? maybe its jsut late and maybe im jsut tired. but thats kinda what i want to do. also if the tec is only puling 120 watts of heat for a 320 watt tec, will it be using less amprage? like i said a real newb you got on your hands. if anyone has anyreasons why this wont work or can tell me what will happen it would be very helpfull! thank you for anyone who can help
3vil

 

[LabRat23]

The wattage rating on a tec refers to how much heat it moves with no temperature difference between the faces. The number is proportional to, but has little to do with the power it consumes. Also, most tecs will have a 68C temperature difference between the faces when there is no heat flow. As the amount of heat moved goes up, the temperature difference goes down. A 220W tec that is moving 110w of heat will have a 34C temperature difference between the faces.

Generally, you will just run 12v on these tecs. The capacity of the tec will go down with a voltage decrease, but there is no tec out there that can run at diminished capacity and still be able to handle a modern cpu. (except for a dothan)

The amount of current it draws does varry a little bit but it is proportional to its hot side temperature, not the amount of heat moved.

 

[3vil_l337]

hey thank you those are the things i needed to hear, so i think i jsut might go to tec with active water besides plain old water. thank you again for the help!
3vil

 

[ls7corvete]

but there is no tec out there that can run at diminished capacity and still be able to handle a modern cpu.

Sure there is... I had success with a 320@5v, at that voltage it kept my 3000+ cooled without problems. I calculated about 180w of cooling capacity while pulling only 10a with that TEC, close to the OP's suggestion of 120w/320w.

can i reduce the the amount of wattage the tec uses (via droping the voltage) and get a same hot side temp with a warmer cold side temp?

Yup, the hot side will be cooler with less voltage because it is removing less heat from the TEC.

will it be using less amprage?

yes, see above.

You should carefully match the TEC to the heat load for the best results, you did not mention your heat load so I cannot comment on if this will work or not.

 

[3vil_l337]

ls7corvete: you have jsut become my best friend. well im going to be cooling a 148 opteron, which is semi low wattage considering. right now it pumping out 95-108 watts of heat. and im guess guessing it is using ~100 average. but when im at theratical max(what my mobo can do volts adn fsb wise) it should only pull about 165-187 or average of 175wats. however i doubt ill get anywhere neer that (using this website to find these http://www.benchtest.com/calc.html ) so yeah my plan was to use a ~300+ tec and run lower voltage/less amperage. and from what your telling me this will work so yeah um thank you again. i think i know where my next few paychecks are going well if you think of anything to point out or think i should know please let me know. youve been a tremdious help! and now i jsut need to buy the stuff thank you one last time
3vil

 

[LabRat23]

Quote:
Originally Posted by LabRat23
but there is no tec out there that can run at diminished capacity and still be able to handle a modern cpu.

Sure there is...

Yeh, your right. I was just in the mindset of the duallies and the pres-hotts.

ls7, Is that the Thermal Enterprises Tec? Take a look at these specs. Thermal Enterprises likes to sugar coat their specs by giving you the performance with a hot side of 50C. At 30C, which is typical of a watercooled Tec IMO, the performance is quite different. I'm not saying you don't have enough capacity, but you might not have as much as you think.

Thermal Enterprises' Tecs

Edit: BTW the 320w Tec is CP1-12730

 

[ls7corvete]

Yeh, your right. I was just in the mindset of the duallies and the pres-hotts.

ls7, Is that the Thermal Enterprises Tec? Take a look at these specs. Thermal Enterprises likes to sugar coat their specs by giving you the performance with a hot side of 50C. At 30C, which is typical of a watercooled Tec IMO, the performance is quite different. I'm not saying you don't have enough capacity, but you might not have as much as you think.

Thermal Enterprises' Tecs

Edit: BTW the 320w Tec is CP1-12730

Yes, I have seen this, I think that the 50c is closer to what I am seeing than the 30c, even at only 5v, so I dont complain. With the full power to that TEC I would be happy so see a Th of 50c, anyone who thinks they can keep that kinda heat down to a mere 5c dT is crazy.

still the biggest TEC I have found in this size. afaik

 

[PoX Freak]

Ok, I have another question on the same subject. Maybe a little "techy" to some, but I'll try anyhow.
I just bought the 12726 TEC from Thermal Enterprises (245/320 watt-15 volt/26 amps), and I am planning a MOSFET controller with a thermistor to regulate volts, so as to not eat up 245-320 watts continuously. I am also planning on air (yes, noisy but effective. the kids make alot more noise), to cool it. I tried this setup with a 172 watt TEC and it worked ok at stock speeds (XP-M 2500+), but got a little hairy above 2200MHz@ 1.65V. Temps jumped up and down from ambient to 10º below.
I guess the question is, what would be better, a PWM/Mosfet setup, or straight up cooling with the 12730? Did I just go over Delta T on the 172 watt unit, or did I not adjust the power to the TEC to compensate?
BTW, the MOSFETs are all P-channel IRF-Z944 (6 total for 480 watts avg dissapation).

 

[3vil_l337]

well i can let you know one thing. and thats dont use pwms unless you get the right frequancy on/off becasue dont do so well with that. and as far as i can see just use strait max power. i cant see any reason not to. anywho i think im going to do phase change anyways (got a old fride ) but if you want the mosfets should work. but air???? on a tec like that? thats going to prety dang big HSF thats for sure. well good luck
3vil

 

[PoX Freak]

Its not a PWM setup at all, just a variation on an older circuit i used for pump speed control in my car ('91 s13 240 sx with a nasty fuel problem. I connected the setup through the TPS, and it balanced my fuel pressure.) I also made a N-channel setup for fan control, which is a variation of an older schematic from some OC site i cant remember. And it is a big heatsink for an athlon XP-M. Get this; ambient is around 22ºC, and with auto fan control, i get 28ºC idle and 34ºC prime 95 at 2.4+GHz/1.675V.
The fan spins at about 1700rpm at idle, and 3500 at load.