Overclock.net › Forums › Cooling › Water Cooling › The importance of the "order" of your loop?
New Posts  All Forums:Forum Nav:

The importance of the "order" of your loop? - Page 4

post #31 of 110
Thread Starter 
Quote:
Originally Posted by Lucretius View Post
I've changed my position on this.

The reason pgmoney gets the temps he does with daisy chained rads is because water temp never reaches the same temp (or higher) as his devices. If your water temp is lower than your device temp, heat energy will transfer to the water.

I don't know much about the rate at which that energy transfers (slows or speeds up) as the two mediums become closer and closer to the same temperature... but I'm sure there is some curve involved there.

If your rads cool the water to near ambient even though they probably don't (lets say 23c, which would be an average air conditioned house at 73f)... then as the water goes through his loop it isn't being heated enough to effect its ability to cool devices that are way higher temp... (53c and 42c)

A system of temp probes would be necessary to verify... or you could just stick a thermometer inside your reservoir and compare the water temperature to the temperature of GPU3.

Here is a total BS conceptual visual of what water temps might be throughout his loop.
Rad: 23c
CPU: 25c (fine for cooling a 53c CPU)
GPU1: 28c (fine for cooling a 42c GPU)
GPU2: 29c (fine for cooling a 42c GPU)
GPU3: 30c (fine for cooling a 42c GPU)

The temperatures in the GPU's do not gradually rise because they are all doing the same work and the water is more than capable of handling all of it.

So even though there are peaks and valleys in the water temperature as it passes through those devices, because of the difference in the temperature of the water and the temperature of the devices and because of the high rate of flow (not allowing any particular gallon of water to absorb much heat), the loop doesn't lose its ability to wick that heat energy away... and wouldn't until there were many more devices in the loop.

Example:
Loop of X number of CPUs and 1 Radiator.
The radiator would be able to cool X number of CPUs where X represents the number of CPUs it takes to produce enough heat energy to raise the temperature of the water to about the same temperature as the CPUs. Where the amount of heat going into the loop is as high as possible without exceeding the amount of heat going out of the loop.
Interesting...makes a lot of sense. Makes me think that a lot of people have more radiator than they need.
post #32 of 110
Quote:
Originally Posted by Lucretius View Post
I'm still curious about what the temperature of the water is at all points on your radiators.

1) Entry Rad 1
2) Exit Rad 1
3) Entry Rad 2
4) Entry Rad 2

It could be that your 2nd rad isn't doing as much as it could, even though it doesn't matter.
i edit 4 for exit not entry

I already measured this a longtime ago and can tell you these numbers now.

1) Entry Rad 1 45c
2) Exit Rad 1 35c
3) Entry Rad 2 35c
4) Exit Rad 2 20c

20c was my ambient temps at the time i measured this. also i think rad 2 cools more because of being external vs. the first being internal mounted.
    
CPUMotherboardGraphicsRAM
core i7 2600K ASUS P8P67 Deluxe EVGA gtx 580 SC 2x4 Corsair Vengence 1600mhz 
Hard DriveOptical DriveOSMonitor
G.SKILL Phoenix Pro 120GB ssd 2x1TB Seagate sony, philips Winodws 7 x64 PRO Hannspree 25" HF259H 
KeyboardPowerCaseMouse
Logitech G19 Enermax evo galaxy 1250 Coolermaster HAF-X CM storm sentineal game 
Mouse Pad
sub zero gamers pad 
  hide details  
Reply
    
CPUMotherboardGraphicsRAM
core i7 2600K ASUS P8P67 Deluxe EVGA gtx 580 SC 2x4 Corsair Vengence 1600mhz 
Hard DriveOptical DriveOSMonitor
G.SKILL Phoenix Pro 120GB ssd 2x1TB Seagate sony, philips Winodws 7 x64 PRO Hannspree 25" HF259H 
KeyboardPowerCaseMouse
Logitech G19 Enermax evo galaxy 1250 Coolermaster HAF-X CM storm sentineal game 
Mouse Pad
sub zero gamers pad 
  hide details  
Reply
post #33 of 110
I've always used gauges, the most important temp is your rad out, that lets you compare your rad out to ambient DeltaT. That shows your rad/fan and loop cooling effectivness.

I did this testing rad shrouds, I was using a rad in and out probe so you can see the drop across the rad...Part 1-Temp's With and With-Out Shrouds

On really overloaded rads with high heat dumps and using high cfm fans I've dropped 2C across my rad. Now those are cheap probes but I've switched leads around on them and they still read about the same.

The coolest point in your loop is always going to be right after the rad. As I've said before it's no great amount and not worth running a lot of extra tubing to get, but if it's easy to run your loop that way I'd do it myself.

If your running low cfm fans you might not drop much at all anyway.
My System
(13 items)
 
  
CPUMotherboardGraphicsRAM
E8600 4545Mhz*9 w/1.29V DFI DK P45 XFX 8800 GS D9GKX & D9GMH 
Hard DriveOptical DriveOSPower
2x Seagate 160 Perp. RD-1 2x Asus Vista Premium Corsair HX 620 
Case
Open Bench 
  hide details  
Reply
My System
(13 items)
 
  
CPUMotherboardGraphicsRAM
E8600 4545Mhz*9 w/1.29V DFI DK P45 XFX 8800 GS D9GKX & D9GMH 
Hard DriveOptical DriveOSPower
2x Seagate 160 Perp. RD-1 2x Asus Vista Premium Corsair HX 620 
Case
Open Bench 
  hide details  
Reply
post #34 of 110
Quote:
Originally Posted by ira-k View Post
I've always used gauges, the most important temp is your rad out, that lets you compare your rad out to ambient DeltaT. That shows your rad/fan and loop cooling effectivness.

I did this testing rad shrouds, I was using a rad in and out probe so you can see the drop across the rad...Part 1-Temp's With and With-Out Shrouds

On really overloaded rads with high heat dumps and using high cfm fans I've dropped 2C across my rad. Now those are cheap probes but I've switched leads around on them and they still read about the same.

The coolest point in your loop is always going to be right after the rad. As I've said before it's no great amount and not worth running a lot of extra tubing to get, but if it's easy to run your loop that way I'd do it myself.

If your running low cfm fans you might not drop much at all anyway.
Isn't that testing pretty invalid considering you were using your TEC and not just straight up water cooling?
post #35 of 110
Quote:
Originally Posted by Lucretius View Post
Isn't that testing pretty invalid considering you were using your TEC and not just straight up water cooling?
I don't think it would matter. It's heat dump, doesn't matter where it comes from.

Quote:
Originally Posted by pgmoney View Post
i edit 4 for exit not entry

I already measured this a longtime ago and can tell you these numbers now.

1) Entry Rad 1 45c
2) Exit Rad 1 35c
3) Entry Rad 2 35c
4) Exit Rad 2 20c

20c was my ambient temps at the time i measured this. also i think rad 2 cools more because of being external vs. the first being internal mounted.
If that's true then your water temp is reaching that of your GPU temps. I would have to imagine some type of heat dump after the first GPU would benefit. But as you claim, you have tested everything.
Edited by Shrimpykins - 8/21/10 at 9:40pm
 
Project Al
(69 photos)
 
CPUMotherboardGraphicsRAM
Intel 2700k Gigabyte UD4 MSI 580GTX Lightning Xtreme Edition 3GB 2x4GB G.Skill @ 1600mhz CL6 
Hard DriveHard DriveOptical DriveOS
OCZ Vertex II SSD OCZ Vertex II SSD LG Blu-Ray/HD-DVD Combo Drive Win 7 Ult 
MonitorMonitorKeyboardPower
Achieva Shimian Acer G235H XArmor U9BL Corsair HX1000W 
CaseMouseMouse PadAudio
Fractal Define R3 Silver Arrow Razer Naga Ultimate Razer Goliathus Speed Edition Polk Audio RTi-A1 
AudioAudio
Dayton Audio DTA-100a Asus Xonar STX 
  hide details  
Reply
 
Project Al
(69 photos)
 
CPUMotherboardGraphicsRAM
Intel 2700k Gigabyte UD4 MSI 580GTX Lightning Xtreme Edition 3GB 2x4GB G.Skill @ 1600mhz CL6 
Hard DriveHard DriveOptical DriveOS
OCZ Vertex II SSD OCZ Vertex II SSD LG Blu-Ray/HD-DVD Combo Drive Win 7 Ult 
MonitorMonitorKeyboardPower
Achieva Shimian Acer G235H XArmor U9BL Corsair HX1000W 
CaseMouseMouse PadAudio
Fractal Define R3 Silver Arrow Razer Naga Ultimate Razer Goliathus Speed Edition Polk Audio RTi-A1 
AudioAudio
Dayton Audio DTA-100a Asus Xonar STX 
  hide details  
Reply
post #36 of 110
Quote:
Originally Posted by Shrimpykins View Post
I don't think it would matter. It's heat dump, doesn't matter where it comes from.
Its a CPU only loop... we're having a conversation about loops that actually might have to do work.

Of course his loop isn't going to change much (less than 1c) because he's effectively cooling nothing.

On top of that, he's not even cooling his CPU... he's cooling his peltier which is cooling his cpu... and has no data about what the temp of his pelt is.
Edited by Lucretius - 8/21/10 at 11:37pm
post #37 of 110
[QUOTE=Lucretius;10436770]Isn't that testing pretty invalid considering you were using your TEC and not just straight up water cooling?[/QUO

Why? 320W heat dump is 320W heat dump. About like an OC'ed chip and a GPU.
My System
(13 items)
 
  
CPUMotherboardGraphicsRAM
E8600 4545Mhz*9 w/1.29V DFI DK P45 XFX 8800 GS D9GKX & D9GMH 
Hard DriveOptical DriveOSPower
2x Seagate 160 Perp. RD-1 2x Asus Vista Premium Corsair HX 620 
Case
Open Bench 
  hide details  
Reply
My System
(13 items)
 
  
CPUMotherboardGraphicsRAM
E8600 4545Mhz*9 w/1.29V DFI DK P45 XFX 8800 GS D9GKX & D9GMH 
Hard DriveOptical DriveOSPower
2x Seagate 160 Perp. RD-1 2x Asus Vista Premium Corsair HX 620 
Case
Open Bench 
  hide details  
Reply
post #38 of 110
I think most people agree that there is a difference in temperature between the input and output of radiator. The question is just how much of a difference is there and how does it affect our system? That is why I in my previous post in this thread wrote that there is hardly any difference because my stance on the subject is that the difference is small and in fact so small that it should not be the dictating factor when deciding loop order.


The following link is to a test that to the best of my understanding empericaly shows that loop order is insignificant:

http://www.xtremesystems.org/forums/...ght=Loop+order



I have also tried to look for help in the theoretical world of physics (in which I am certainly no expert so excuse me if I make a mistake in my calculations). I have tried to make some assumptions about a typical system and then tried to calculate the theoretical difference between input and output temperature of the radiator.


Assumptions:
  1. All components water cooled is daisy chained and the readiator is daisy chained as well. The radiator is placed after the components (worst case scenario)
  2. The water cooled components produce 500W of energy that is dumped (might correspond to one serious GFX card, CPU, mother board cooling and pump heat dump)
  3. Flow rate: 2 GPM (this is a flow many aim at or want to exceed)
  4. The system is fully loaded and water temperature has reached equilibrium


Theory:
Equilibrium:
When the computer is turned on the water is at room temperature. Since there is no difference between radiator temperature and ambient there will be no heat removed by the radiator. However, there is a big difference between CPU temperature and water temperature so a lot of the CPU heat will be removed (and the CPU runs at it coolest possible). Since heat is added and none removed (only at the start) the water temperature will rise. As soon as it does the radiator will start to remove heat. In the beginning less heat is removed than added by the components because heat transfer is liniar to the difference between radiator temperature and ambient and that difference is still small. So water temperature continues to rise. At some point the radiator will remove exactly the same amount of heat as add by the components. If this where not the case the water would eventually start to boil (assuming that heat is only removed at the radiator which I think is fair and conservative assumptions). This is the point I call equilibrium. If the workload changes the equilibrium will change as well. For this discussion the worst case is when the CPU and GPU working out to the max because this will yield the biggest heat dump into the water and hence mean that the biggest heat removal by the radiator which again means the biggest temperature difference between input and ouput.


The heat flow equation:

Q = m * c * dT

Where
  • Q = Heat (measured in Joules. 1 joules = 1 Watt second)
  • M = mass (in this case the mass of the water going through the radiator in the timeframe we calculate over)
  • c = Specific heat or heat capacity per unit mass of a body. This variable is dependent on: the material used (which in this case is water), its temperature and the presure. For water it is close to 4 J/G*C at 15C and 101.325 kPa). I dont think it changes much at other temperatures and preasures but this is where my physics knowledge ends.
  • dT = Change in temperature.


We can use this formula to calculate the theoretical change in temperature between input and output of the radiator.


Calculations
What we know:
  • 2 gallons of water passes through the radiator each minute. This corresponds to about 7.5 Liters of water/minute which equals 125ml/second. 125ml of water weights (approximately) 125g. so M = 125g in our formula above
  • 500W needs to be removed by the radiator (since 500W is added by the components we know 500W must be removed as well since we are in equilibrium). We know the amount of heat removed is Q = 500 W * seconds
  • c = (approx) 4 J/(g*C) = 4 Ws/(g*C) , C = celcius, remember 1 Joules = 1 Ws per definition
  • dT = temperature difference we want to compute.

Entering these values into the heat flow equation yields:

500 Ws = 125g * 4 Ws/g*C *dT

==>

500 Ws = 500 Ws/C * dT

==>

dT = 1.0 C


So theoretically there should be a 1 degree difference in temperature between input and output of the radiator. If 1000W of energy is added the difference would be 2C and so forth.


Conclusion:

From the above (and assuming I made no mistakes in my application of the formula) I personally conclude:
  1. There is a difference. However, it is small.
  2. The difference in input/output is not enough for me (even for a big system) to dictate loop order. I would personally prefer tidyness, simplicty and reduced tubing (easier to bleed, fill, drain...).
  3. Also look at what happens if you spread out the radiators (typically 1 before CPU, 1 after CPU) between each block. Then the radiators share the work of removing the heat and the difference in input/output temperature of EACH radiator will be less.
  4. A good question now is: What does a 1C improvement in water temperature do to the CPU tempeature. My guess is very little - a guess that is backed up by the people who says they tried different loop orders without any change in CPU temperature.
  5. If one insists on the importance of loop order the above indicates you should put all radiators in series and place them right in front of the CPU to get biggest temperature drop before the water hits the CPU block.



Gah. this took quite a while to figure out and write. I hope it will be useful reading . This is why water cooling is fun... .


/Nordar
Edited by Nordar - 8/22/10 at 3:56am
My System
(17 items)
 
  
CPUMotherboardGraphicsRAM
6700k I7 Asus Hero VIII MSI 980Ti 16GB 3200 DDR4 
Hard DriveHard DriveHard DriveHard Drive
Intel 750 400GB  OCZ Vertex 2 100GB  HGST Deststar 4TB WD Caviar Black 2 TB 
CoolingOSMonitorKeyboard
XSPC Rads, EKWB blocks, Gentle Typhoons Win 10, Pro 64 bit Dell 27", 1440P Das Keyboard 
PowerCase
Silverstone Strider ST-1500 Lian Li PC-A77B 
  hide details  
Reply
My System
(17 items)
 
  
CPUMotherboardGraphicsRAM
6700k I7 Asus Hero VIII MSI 980Ti 16GB 3200 DDR4 
Hard DriveHard DriveHard DriveHard Drive
Intel 750 400GB  OCZ Vertex 2 100GB  HGST Deststar 4TB WD Caviar Black 2 TB 
CoolingOSMonitorKeyboard
XSPC Rads, EKWB blocks, Gentle Typhoons Win 10, Pro 64 bit Dell 27", 1440P Das Keyboard 
PowerCase
Silverstone Strider ST-1500 Lian Li PC-A77B 
  hide details  
Reply
post #39 of 110
All that, for WC
i7 930
(13 items)
 
  
CPUMotherboardGraphicsRAM
i7 930 [4.0@1.23v] [4.2@1.32v] ASUS P6T-Deluxe [v1] EVGA GTX 480 SC+ [850/2000@1.100v] OCZ Gold DDR3 [3x2GB] [1600@8-8-8-24-1N] 
Hard Drive
OCZ Vertex 2e (120GB) SSD 
  hide details  
Reply
i7 930
(13 items)
 
  
CPUMotherboardGraphicsRAM
i7 930 [4.0@1.23v] [4.2@1.32v] ASUS P6T-Deluxe [v1] EVGA GTX 480 SC+ [850/2000@1.100v] OCZ Gold DDR3 [3x2GB] [1600@8-8-8-24-1N] 
Hard Drive
OCZ Vertex 2e (120GB) SSD 
  hide details  
Reply
post #40 of 110
Quote:
Originally Posted by Trigunflame View Post
All that, for WC
Not really, all that to prove that loop order is mostly inconsequential to performance.

Wes
R3E
(13 items)
 
  
CPUMotherboardGraphicsRAM
i7 920 Asus R3E MSI 295 GTX (Single PCB) 12GB 
Hard DriveOptical DriveOSMonitor
500GB DVD-R Windows 7 64bit 20inch Apple LCD 
KeyboardPowerCaseMouse
Apple Keyboard Corsair 850w Lian Li Medium Tower Razer 
  hide details  
Reply
R3E
(13 items)
 
  
CPUMotherboardGraphicsRAM
i7 920 Asus R3E MSI 295 GTX (Single PCB) 12GB 
Hard DriveOptical DriveOSMonitor
500GB DVD-R Windows 7 64bit 20inch Apple LCD 
KeyboardPowerCaseMouse
Apple Keyboard Corsair 850w Lian Li Medium Tower Razer 
  hide details  
Reply
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Water Cooling
Overclock.net › Forums › Cooling › Water Cooling › The importance of the "order" of your loop?