Dual Loop versus Single, the facts

[gabe]

thats not a dual loop barf... lol..

While u get advance in our hobby a dual loop is the route, because of the more fine control you get, and when setup properly, you get better efficiency in your loops for lower deltas.

1/ Pls qualify/elaborate (with data if possible) "setup properly"

2/ By "While u get advance in our hobby" do you mean something like your own setup (3 independant loops on 4 radiators and 6 pumps)?

3/ Other members comments/input request: is Naekuh's setup representative of the average XS member?

4/ Have you tried to connect your 3 loops in series? and if so, would you share the data?

[NaeKuh]

1/ Pls qualify/elaborate (with data if possible) "setup properly"

2/ By "While u get advance in our hobby" do you mean something like your own setup (3 independant loops on 4 radiators and 6 pumps)?

3/ Other members comments/input request: is Naekuh's setup representative of the average XS member?

4/ Have you tried to connect your 3 loops in series? and if so, would you share the data?

1. because your still dealing with carrying capacity of water, you will get a higher delta from inlet and outlet in your system.
Gabe, if you have 3 monster class GPU's + an assortment of blocks where it crimples your flow, you cant tell me by not separating them out your not going to get better performance.
The lowest you can go is ambient... the highest you can go will be determined by how much flow you have in relationship to how many blocks are connected in a series with the overall radiator capacity.

2. By advances i mean as you get more skilled and you want customization. Are you telling us ONLY to use single loops and conform to the mac way? im sorry, but watercooling is about customization, how you build it and how you use it is totally up to the op. Telling a person the single loop is always the best and only way is blatantly wrong.

3. My system is no where near the average, its what happens after you stuck with this hobby for a very long time with a lot of resources outside of being a vendor. I can count more then a handful of systems in the worklog which would rival mine and possibly even beat it.

4. Yes i have... with everything loaded it was terrible. Were talking about 3 x 580GTX + full board block (which is given to kill flow) + cpu block. I have TOO MUCH stuff on 1 loop, if i add too many DDC's in a series my flow only goes up 1/3 for each DDC i added, and they get WORKED harder and heat up faster. Gabe have u ever attached 3 ddc's + in a series and seen how hot they run? ignoring the 35x...


Now i said single loops are ideal for the starter, who doesnt need to worry about the cache of blocks.
But not everyone is solely on just your blocks.
We use board blocks, mosfet blocks, some guys even use ram blocks.. EACH of these require flow.
To a certain point you can only get so much because water can only carry so much.

Now dont get me wrong, if your happy with your 10+ Deltas dont let me stop you... but i didnt water for that. And i sure many others will follow my shoes and strive for lower temps over bling.
If your a starter, a 10C delta might seem wow, as you get advance its dismal... you get greedy like all human nature and you strive for the less then 5C delta, even the 2C delta.
Which isnt possible in your model with EVERYTHING LOADED on the cache of blocks i have, without damaging my pumps in the future from overworkage by having too many in a series.

Its not exactly a single loop though either. If 1 set of pumps fails, i wont have flow to that part of the loop.

I think of myself as advanced, just because i dont have your setup (Then again i dont ahve a MM Acension + Pedestal to fit 6 rads into anyways, and i dont want one either.... i have enough bar stools/couch tables), doesnt make me less advanced.

This is my system.

not sure if you can make it out, but the left side of the bench, is the CPU only loop, and the right side is for everything else.

It has dual d5's on each "loop". if both pumps on one side die, that loop (either CPU, or GPU/ram/mobo) wont get any flow... I have the ability to turn on/off the pumps, and ive tested to see (with a flowmeter) if one side shuts down if it will get any flow.... it doesnt. Can you please explain to me where you assumed that it would get flow?

Im sorry i should of clarified the terminology advance...
It means as you know what each thing does in relationship to how it works, as your customizing, you plan things out accordingly so it works within the set parameters you want it to work at.
This means sometimes you will have to go outside the normal way things are done, and improvise, or innovate new ways to get the job done.

When i say advance.. it typically means, when you planned your loop, you didnt ask for help, you didnt use any resources because your brain is already a mountain of resources.

And Barf, a single loop is always a single loop if 1 component on each loop is shared regardless of how its split up.
A closed loop works on equalibirum, meaning it tries to hold constant until you exceed the maximum holding potential of water where the water temp slowly rises in a gradient form inside your loop.
Your sharing the res, that means as your pulling water from the res, your pumping it back, you will get some movement inside that second portion of the connection inside your res.. it maybe small, but its still a off parallel loop model because your sharing the res. Flow is just very dismal inside that second portion of your parallel because of the imbalance in restriction, which your second pump helped negotiate.

We never had this problem b4, GPU's didnt put out much heat (No one really SLI'd and when you sli'd it ended at 2 and Xfire was even rarer) and cpu's didnt, unless u were on a kentsfield under constant load all the time... there was no board blocks til Bitspower, Bei and I started innovating, so there was no true flow killers out there (Except the EK supreme).
Gpu blocks were just solid slabs of copper with channels (not micro channels which are more efficient) and now have they have water channels on the vrm's so they pick up even more heat.

We didnt have these options, but we do now... things add up, nothing in the world is for free, and everything comes at a cost unless you pay for the cost. <-- this is the rule of thermo.

[stephenswiftech]

1. because your still dealing with carrying capacity of water, you will get a higher delta from inlet and outlet in your system.
Gabe, if you have 3 monster class GPU's + an assortment of blocks where it crimples your flow, you cant tell me by not separating them out your not going to get better performance.
The lowest you can go is ambient... the highest you can go will be determined by how much flow you have in relationship to how many blocks are connected in a series with the overall radiator capacity.

2. By advances i mean as you get more skilled and you want customization. Are you telling us ONLY to use single loops and conform to the mac way? im sorry, but watercooling is about customization, how you build it and how you use it is totally up to the op. Telling a person the single loop is always the best and only way is blatantly wrong.

3. My system is no where near the average, its what happens after you stuck with this hobby for a very long time with a lot of resources outside of being a vendor. I can count more then a handful of systems in the worklog which would rival mine and possibly even beat it.

4. Yes i have... with everything loaded it was terrible. Were talking about 3 x 580GTX + full board block (which is given to kill flow) + cpu block. I have TOO MUCH stuff on 1 loop, if i add too many DDC's in a series my flow only goes up 1/3 for each DDC i added, and they get WORKED harder and heat up faster. Gabe have u ever attached 3 ddc's + in a series and seen how hot they run? ignoring the 35x...


Now i said single loops are ideal for the starter, who doesnt need to worry about the cache of blocks.
But not everyone is solely on just your blocks.
We use board blocks, mosfet blocks, some guys even use ram blocks.. EACH of these require flow.
To a certain point you can only get so much because water can only carry so much.

Now dont get me wrong, if your happy with your 10+ Deltas dont let me stop you... but i didnt water for that. And i sure many others will follow my shoes and strive for lower temps over bling.
If your a starter, a 10C delta might seem wow, as you get advance its dismal... you get greedy like all human nature and you strive for the less then 5C delta, even the 2C delta.
Which isnt possible in your model with EVERYTHING LOADED on the cache of blocks i have, without damaging my pumps in the future from overworkage by having too many in a series.



Im sorry i should of clarified the terminology advance...
It means as you know what each thing does in relationship to how it works, as your customizing, you plan things out accordingly so it works within the set parameters you want it to work at.
This means sometimes you will have to go outside the normal way things are done, and improvise, or innovate new ways to get the job done.

When i say advance.. it typically means, when you planned your loop, you didnt ask for help, you didnt use any resources because your brain is already a mountain of resources.

And Barf, a single loop is always a single loop if 1 component on each loop is shared regardless of how its split up.
A closed loop works on equalibirum, meaning it tries to hold constant until you exceed the maximum holding potential of water where the water temp slowly rises in a gradient form inside your loop.
Your sharing the res, that means as your pulling water from the res, your pumping it back, you will get some movement inside that second portion of the connection inside your res.. it maybe small, but its still a off parallel loop model because your sharing the res. Flow is just very dismal inside that second portion of your parallel because of the imbalance in restriction, which your second pump helped negotiate.

We never had this problem b4, GPU's didnt put out much heat (No one really SLI'd and when you sli'd it ended at 2 and Xfire was even rarer) and cpu's didnt, unless u were on a kentsfield under constant load all the time... there was no board blocks til Bitspower, Bei and I started innovating, so there was no true flow killers out there (Except the EK supreme).
Gpu blocks were just solid slabs of copper with channels (not micro channels which are more efficient) and now have they have water channels on the vrm's so they pick up even more heat.

We didnt have these options, but we do now... things add up, nothing in the world is for free, and everything comes at a cost unless you pay for the cost. <-- this is the rule of thermo.

Water doesn't loose its physical properties with heat load. Heat load tends to increase water temperature but if you have a system that can maintain your water temperature at a decent level, it doesn't matter how much heat load is going through, water still has the same properties.

I've asked you several times to explain precisely what you mean with "holding capacity of water" because it does look like you are mixing things up.

[NaeKuh]

I've asked you several times to explain precisely what you mean with "holding capacity of water" because it does look like you are mixing things up.

Martin + Skinnee + Vapor + others i remember long ago HASHED this forumla out.


it translated to 300W per 1 gallon per minute flow in pure distilled h2o.
http://en.wikipedia.org/wiki/Heat_transfer_coefficient

From the above equation, the heat transfer coefficient is the proportional coefficient between the heat flux that is aheat flow per unit area, q/lund, and the thermodynamic driving force for the flow of heat (i.e., the temperature difference, ΔT).


if im lost somewhere please teach me stephan.. your one of the guys i know who knows LC and thermo.

But watercooling in its basics is..

Heat is being released in blocks... water picks up... carries.. and then dumps.
That means when water picks up heat, it picks up energy and MUST increase in temp.
That number of Energy is in a relationship between flow and medium that is being used.. ie.. distilled water.
Water is non compressible, so were not going have crazy values which compressed gasses like LN2 would have as there is no evap involved.

Saying water WONT go up 1 degree after touching a X amount of heat is breaking the laws of physics.

So how much of a gradient is acceptable? or better yet do you even have a gradient?
If your a new user.. typically your gradiant wont be larger then 1C.

If you have 3 580gtx under load, with a full board block with a cpu block and a ram block, and you watercool your aquero controlller along with an ARC-1680ix... well... as i said, you need to pay for somethings.

For the only reason that the motherboard full cover block is so restrictive, it kills the flow even with dual pumps. So i have dual pumps on the CPU+GPU loop, and a single pump on the motherboard loop.

yeah i wish people understood this..
the bridge on the nb -> Sb only allows so much without making it bulky.

Which is why the barb locations on most is made so you could connect a gpu to them without much trouble.

[stephenswiftech]

Martin + Skinnee + Vapor + others i remember long ago HASHED this forumla out.


it translated to 300W per 1 gallon per minute flow in pure distilled h2o.
http://en.wikipedia.org/wiki/Heat_transfer_coefficient

From the above equation, the heat transfer coefficient is the proportional coefficient between the heat flux that is aheat flow per unit area, q/lund, and the thermodynamic driving force for the flow of heat (i.e., the temperature difference, ΔT).


if im lost somewhere please teach me stephan.. your one of the guys i know who knows LC and thermo.

But watercooling in its basics is..

Heat is being released in blocks... water picks up... carries.. and then dumps.
That means when water picks up heat, it picks up energy and MUST increase in temp.
That number of Energy is in a relationship between flow and medium that is being used.. ie.. distilled water.
Water is non compressible, so were not going have crazy values which compressed gasses like LN2 would have as there is no evap involved.

Saying water WONT go up 1 degree after touching a X amount of heat is breaking the laws of physics.

So how much of a gradient is acceptable? or better yet do you even have a gradient?
If your a new user.. typically your gradiant wont be larger then 1C.

If you have 3 580gtx under load, with a full board block with a cpu block and a ram block, and you watercool your aquero controlller along with an ARC-1680ix... well... as i said, you need to pay for somethings.



yeah i wish people understood this..
the bridge on the nb -> Sb only allows so much without making it bulky.

Which is why the barb locations on most is made so you could connect a gpu to them without much trouble.

what exactly are you trying to show with this equation? "A" in your equation is the surface area on which you are calculating "h" - fluid properties have nothing to do with that. That doesn't explain where your "holding capacity of water" is coming from. This formula has nothing to do with the problem here.


When designing liquid cooling systems the only relevant equation would be: Q [W] = Flow [Lps] * Cp [J/Kg/K] * DT [K]

W is the amount of heat (in W)
Cp is the specific heat for Water (or Heat Capacity) and is equal to 4186 J/Kg/K.
Flow in Liter per second.
and DT is the difference in temperature between 2 points.

it only gives you the relation between the amount of Heat that is going through your liquid cooling system and the temperature delta between inlet and outlet.
you can use this formula to calculate the amount of heat that is going through any component of your loop: radiator, water block, etc (provided you precisely know your flow rate, and temperatures). Also note that formula is good way to decently approximate how much heat a CPU or GPU is putting into your LC system.

so if you take a CPU or GPU that puts out 200W - with a flow rate of 1 GPM (say 4LPM for easier calculations), your DT = 600 * 60 / (4 * 4186) = 2.15 C
Now say you run 4 of these: 3x GPU's and 1 CPU, that's 800W. Each of them increases the coolant temperature by 2.15C. let's keep things simple, say they're all in series, that's a total DT of 8.6 C.

Now we just gotta figure out what the coolant temperature is at the radiators outlet.

two MCR320-QP have a combined thermal resistance of 0.012 C/W at 4 LPM. For 800W heat load the coolant temperature will be 9.6C higher than ambient. If the ambient is 20 C, that's 29.6 C at the rad outlet (and at the radiators inlet you'll have 29.6 + 8.6 = 38.2 C).


See there is nothing here that remotely suggests a "limit" or even a sweet spot... If there is a limit, it is something you personally came up with based on your experience. But that is completely different than stating there is a limit and that is coming from the heat transfer formula you linked. And don't tell me water properties change with temperature because these variations exist but are irrelevant: Cp (I.E. water properties) is almost independent from temperature (4182 @ 20C ... to ... 4196 @ 80C) - so really water properties don't change - at least in the range that is usable by LC systems.



This was pretty much off topic... Anyways back on topic you disagree with the actual results shown in this thread - which is fine. But my problem is that you try to prove your point by stating there is a limit and that, basically single loop systems are going to be passed this limit and that is bad. Nope, there is no 300W limit with LC systems whether it's for computers, cars or anything. The only physical limit are coolant properties but here again they don't vary in any relevant way. In the 20 to 50C range of coolant temperatures (that probably covers 99% of the systems) it's all nice and linear: like you said xxx Watts = yyy C at zzz Lpm.

The only good point you make is bringing up the fact that Gabe's results prove single loops are the way to go for systems that take care of CPU and GPU when they are not all loaded at the same time. If we were to load up both CPU and GPUs all at the same time, then dual loops would probably end up each with a slightly higher flow rates, but not by much, which "could" result in slightly better temps but again not by much! Keep in mind that with the hardware to build 2 loops, you have at least 2 pumps and 2 radiators. There is no problem going in a CPU first then into a radiator, then into the GPUs and then into another radiator. This will smooth out the coolant temperature at the inlet of the blocks.

Also, unless you run 4 pumps, by going dual loops you will lose redundancy (as opposed to a single loop with 2 pumps in series). And anyway, who is loading CPU and GPUs at the same time? I am sure there are people who do that, I am one of them when I stressing our kits for pure testing purposes but is this the majority? I really don't think so.

[rge]

so if you take a CPU or GPU that puts out 200W - with a flow rate of 1 GPM (say 4LPM for easier calculations), your DT = 600 * 60 / (4 * 4186) = 2.15 C
Now say you run 4 of these: 3x GPU's and 1 CPU, that's 800W. Each of them increases the coolant temperature by 2.15C. let's keep things simple, say they're all in series, that's a total DT of 8.6 C.

unit conversion error?

Q watts (joules/second) = mdot * Cp*dt = 1 gal/min x 8.34/lbs/gal x (1min/60sec) x (.4536 kg/1lbs) x 4186 Joules/KG C x 1 C = 264W.

I get 264 Watts to heat water by 1C at 1 gal/min. For a delta of 2C, would take 528W

Just dont want people thinking that after 2 gpus = 4C difference, or will be constantly dealing with posts about loop order.

[stephenswiftech]

unit conversion error?

Q watts (joules/second) = mdot * Cp*dt = 1 gal/min x 8.34/lbs/gal x (1min/60sec) x (.4536 kg/1lbs) x 4186 Joules/KG C x 1 C = 264W.

I get 264 Watts to heat water by 1C at 1 gal/min. For a delta of 2C, would take 528W

Just dont want people thinking that after 2 gpus = 4C difference, or will be constantly dealing with posts about loop order.

Possibly, I made the approximation that 1gal = 4LPM (I used 4LPM in my post) and made the approximation that 1Kg = 1L
You get the idea

[NKrader]

3/ Other members comments/input request: is Naekuh's setup representative of the average XS member?

oh yeah