The Tech Repository Forums  

Go Back   The Tech Repository Forums > Member Discussions > Cooling/Thermal Management
FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Rating: Thread Rating: 8 votes, 5.00 average. Display Modes
Old February 28th, 2007, 06:33 PM   #1
PC_kIlLeR
New Member
 
PC_kIlLeR's Avatar
 
Join Date: Feb 2007
Question In what order should water cooling components be installed?

hi all. first, i would like to thank Tony for his great guide and explanation for the P5B Deluxe. it was your guide that brought me here. back to my problem, i just bought a COOLER MASTER RL-HUC-E8U1 Liquid Cooling System and a Thermaltake CL-W0002 12-cm big radiator. what order should the water cooling be connected for maximum cooling?

Pump > Radiator > CPU block > GPU block > Back To Pump

Pump > CPU block > GPU block > Radiator >Back To Pump
PC_kIlLeR is offline   Reply With Quote
Old March 2nd, 2007, 12:49 PM   #2
freecableguy
System Fungineer
 
freecableguy's Avatar
 
Join Date: Sep 2006
Location: Santa Clara, CA
Send a message via Skype™ to freecableguy
In 99% of watercooling systems there is no "optimal" component ordering, EXCEPT that which minimizes tight bends and overall tubing length. This is not always true as there can be a significant difference (read: measurable) when dealing with extremely high heat loads, like those found in systems in which one or more components are actively cooled by a TEC. Because of water's high heat capacity, there is very little change in water temperature due to the heat dump from components that may be considered "parasitic" to the loop's most efficient operating conditions. What do I mean by this? In your case, this only really applies to the pump.

Example:

Specific heat of water (c) = 4.186 J/gram-C

By definition 1 Joule (unit of energy) = 1 Watt-second (unit of power)

therefore, c = 4.186 W-sec/gram-C

Meaning, if you pump "dumped" a modest 15W of heat into your loop:

Q = cm(ΔT) where Q is the heat added (15W), c is the specific energy of the material "receiving" the heat energy (water), m is the mass of the material, and delta T is the rise in temperature of the material.

Since this would ultimately depend on flow rate (to be given as g/sec, L/hr, gal/min or whatever other units you desire) we are going to simplify our example by assuming your flow rate is 2L/min:

(2L/min)(1 min/60 sec)(1000 g/1L) = ~42 g/sec (1L water = 1000 g by definition)

Q = cm(ΔT) => 15W = (42 g/sec)(4.186 W-sec/g-C)(ΔT) -> ΔT = 0.08 C

As you can see, certainly not a lot of temperature rise due to the pump alone. So assuming the water temperature entering the pump was 25C exactly, this would mean that the outlet temperature from the pump would be 25.08C. If the CPU (or any other block) was located such that the outlet of the pump directly feed it then the supply temperatures would be 25.08C! (assuming that your tubing was a perfect insulator)

Try repeating this calculation with higher flow rates (3L/min, 4L/min, etc.) and you will see that in any case there is not much to be gained by sending the water from the pump through the radiator before any cooling block/device. In fact, due to the extremely small water temperature increase from to the pump I'm no so sure you would see ANY difference in radiator outlet temperature (a passive heatsink's ability to reject heat is directly proportional to the difference in temperature between the medium being cooled and the medium providing the cooling, in this case air at ambient).

Finally, since the GPU and CPU block locations are the only other real question, I can only provide you with the same advice. Using the equation above you can calculate the approximate rise in water temperature across the block (I say approximate because Q in the given equation can only be approximated from true processor power consumption since calculations, as provided, would have to assume that 100% of the heat from the processor is transmitted to the block and then to the water, which is untrue...). Then it's just a matter of determining which component you think needs that extra degree or two of cooling to perform best. At this point it's really a matter of preference and/or individual testing (which would require that you test the loop with each block individually installed, to remove the other as a competing variable, and then plotting the overclock results as a function of supply water temperature).

I hope I've at least partially answer your question. If not, here's the bottom line: I believe you will find that there is little to no performance difference to be achieve by ordering components in your loop. Instead, work to minimize flow resistance (smooth tubing bends and as little tubing used as possible). Any optimizations here will allow for maximum flow (see here) possible. The key to flow rate? MORE flow is ALWAYS better. There, I said it. Those that think otherwise are out to lunch. Note: PLEASE, PLEASE, PLEASE...don't write or post telling me about how more flow requires more powerful pumps which dumps more heat, etc....I know this and I am not going to argue a fact such as that. I am simply saying that a higher flow rate will always produce smaller thermal gradients all the way down to the CPU-to-IHS interface.

-FCG
freecableguy is offline   Reply With Quote
Old March 2nd, 2007, 10:34 PM   #3
PC_kIlLeR
New Member
 
PC_kIlLeR's Avatar
 
Join Date: Feb 2007
thanks a lot for the long explanation. i was almost going to put up a test after my dual heater core came. before reading what u have wrote, i thought that pump to radiator should be how the loop starts. now it's all clear up to me but i have no clue about the two pump thread . btw, i read your other thread about removing intel's IHS. if the IHS is to be removed, would there be at least an extra 5-10 degree celsius drop in temperature with water cooling?. i already removed the IHS on my intel 478 chip with air cool (intel stock aluminum heat sink) and there is no drop in temperature at all.
PC_kIlLeR is offline   Reply With Quote
Old June 3rd, 2007, 01:26 PM   #4
Liquid3D
New Member
 
Liquid3D's Avatar
 
Join Date: Jan 2007
Location: New England, Connecticut Shoreline
Send a message via MSN to Liquid3D
I've tested this any times and there are reasons it matters, however; a much more important question then the order is the location of components especially fan placment and airflow direction. I mean absolutely no dis-respect but this is what most mathematic formula's and tables fail to include.

For these reasons I give the following example re-prioritizing. Lets say you use the this order:

pump > CPU > GPU > reservoir > radiator

what's important here is the radiator's location in the system - if the radiator is mounted inside the case at the rear with fans mounted externally pulling the case air through the Radiator, or mounted inside the pushing air in both you've placed your heat-exchanger (Radiator) in the least effective position, as part of the exhaust.

Your room's ambeint temp will ALWAYS (and I don't usually use universal quantifiers) be lower then air within your enclosure pre-heated by micro-circuitry. In this scenario your CPU temp will never be lower then the internal air temp of the case.

As we know internal case temps are often 20C + higher then a room's ambeint temp, some even higher, very few are lower. Passing pre-heated air through your radiator will eventually raise the water temp to match the air-temp per the rule of Thermal Equilibrium which states:

It is observed that a higher temperature object which is in contact with a lower temperature object will transfer heat to the lower temperature object. The objects will approach the same temperature, and in the absence of loss to other objects, they will then maintain a constant temperature. They are then said to be in thermal equilibrium. Thermal equilibrium is the subject of the Zeroth Law of Thermodynamics.


Of course there is a "slight loss" as the case itself will dissipate heat to the environment, however; convection or radiation uses air which isn't the best medium and thermal equillibrium will almost always occur.

What I suggest is this, lets say your using a Dual 120 raditor and mountin it at the rear of your case albeit mounted externally, or internally. Then the fans regardless of their pacement internal or external, shoul be pulling or pushing ambeibnt air through the radiato. Yes this asks you reverse case air-flow, but the alternative is far less apealling as it defeats the purpose of H20 cooling.


In that system I will use the following order:


pump (internal) > radiator (external) > CPU (internal) > GPU (ibid> > reservior (ibid)


Personally I wouln't cool mutiple chips (CPUs and today's high end GPUs) using a Dual Rad anyway. Although the Core 2 Duo is a low TDP processor, water exiting that block carries that heat right to the GPU and if it's GPU/memory cooler H20 hjeated by the GPU then flows over VGA memory.

In the VGA world, overclocking the mmory almost always provides better performance then overclocking the GPU, ergo the H20 flow priority should concenrate on th VGA memory first wheretemps will be lower and then to the GPU. There are many ways to accomplish this. Purchasing GPU waterblocks and then seperate VGA memory water-blocks. It still won;t mater much as your cooling our graphic card with pre-heated water. Therefore I have another suggestion:

pump > dual-radiator (externally mounted) > CPU > single radiator (mounted in front of case) > GPU > reservoir

System pressure will be fine if your using a pump with decent head-feet, LAING D5-38 Vario (12-ft max), LAING D5-Strong (20-ft max)

I completely agree the temperature of water passing through a pump is nary affected, but the same is not true where radiator and fan placement are concerned including air-direction. Placement of your radiator and fans can have a substantial affect on CPU temp and -20C will easily make the difference between a 50% overclock and a 80% overclock.

IMHO
__________________
E6400 (8x400FSB)
AM2 Opteron 1212 (10x300FSB)
DFI Infinity ULTRAII-M2
Asus P5W DH
Gigabyte GA-965 DS3
Leadtech 7950GX2
BFG 8800GTX
PCPower&Cooling Silencer 750W
PCPower&Cooling 1KW
Danger Den NVIDIA 4101 7/16
Sub-Zero H20, Oase pump, Dual Rad 10mm
Liquid3D is offline   Reply With Quote
Old June 3rd, 2007, 06:15 PM   #5
freecableguy
System Fungineer
 
freecableguy's Avatar
 
Join Date: Sep 2006
Location: Santa Clara, CA
Send a message via Skype™ to freecableguy
I'm not going to address every point of your post, but there a couple that I think need some bit of attention because of what I would almost call a "gross concept error."

Quote:
Your room's ambeint temp will ALWAYS (and I don't usually use universal quantifiers) be lower then air within your enclosure pre-heated by micro-circuitry. In this scenario your CPU temp will never be lower then the internal air temp of the case.
You're right, although for what appears to be the wrong reason. I would agree with you 100% of the time - without some kind of enery input (ie. active energy rejection) your CPU temperature will never be below ambient. (Ambient being the temperature of the air entering the radiator, whatever the source.)

Quote:
Placement of your radiator and fans can have a substantial affect on CPU temp and -20C will easily make the difference between a 50% overclock and a 80% overclock.
If your case temperature is 20C higher than the room temperature you may have a serious ventilation problem. While it makes perfect sense that the case interior be hotter this is a little too much for my comfort.


Otherwise, although I do think your brings up some good points for thought, I don't think it remains on topic. The original discussion was regarding loop order -- not radiator placement (external vs. internal) and fan usage.



-FCG
freecableguy is offline   Reply With Quote
Old May 28th, 2008, 06:42 PM   #6
freecableguy
System Fungineer
 
freecableguy's Avatar
 
Join Date: Sep 2006
Location: Santa Clara, CA
Send a message via Skype™ to freecableguy
Parallel paths are generally a bad idea. Unless you can ensure that the hydraulic resistance for each flow path are equal you'll end up with a situation where the path of least resistance will receive a disproportionate share of the flow. Keep everything series unless you want to deal with these types of concerns...
freecableguy is offline   Reply With Quote
Old May 28th, 2008, 11:34 PM   #7
freecableguy
System Fungineer
 
freecableguy's Avatar
 
Join Date: Sep 2006
Location: Santa Clara, CA
Send a message via Skype™ to freecableguy
Of course! The water coming from the CPU will not be anywhere near the actual CPU die temp. Let's say ambient is 22C, and the water is on average 5C higher (27C)...depending on the actual CPU heat load I wouldn't expect to see the outlet temp of the CPU block to be much higher than 29C, given proper flow and radiator cooling. This is the same water that then cools the GPU, which will present a GPU block to water delta of at least 10C or more.
freecableguy is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 07:20 PM.


Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
The Tech Repository