1 Big Loop vs 2 Loops?

So, here is what I have. I've Laing DDC DDCT-01s pump, EK-RES250 reservoir and Thermochill Pa 120.2 Dual 120MM and Thermochill Pa 120.3 Dual 120MM connecting:

Res => Pump =>CPU => 8800GTX => 8800GTX => Rad 120.3 => Rad 120.2 =>Res.

Now that I'm upgrading my Board and CPU, I thought EK-Bay Spin Reservoir would look cool in front bay. I've 2 of these Laing DDC DDCT pumps (petra tech's). What should I do to utilize this EK bay res and pump (not necessarily both, but one if is enough like it is now). Since EK-Bay Spin has three outlet, I was thinking atleast using 2 outlets straight like

Reservoir Out1 => CPU => Rad 120.2 =>Res

Reservoir Out2 => GPU => GPU = Rad 120.3 =>Res

or should keep it same as before and keep 2 other outlets blocked?

May be I wasn't clear... no replies???

well, what I was thinking is

Res => PUMP => CPU => Small Rad and back to Res.

Res => PUMP => GPU1 => GPU2 = Big Rad and back to Res

where back to Res with Y-Plug since Res has only 1 inlet. So both Radiators outlets to 1 inlet of Reservoir.

Since CPU to GPU 1, water may become hot and from GPU1 to GPU2, it become even more hot so the GPU2 (poor thing) is taking the most heat Smile

What do you think?

Single (big) loop is simple and easy and I think 1 pump should be sufficient also...

I would do one loop, and run both GPUs in parallel.
Something like this
res -> pump -> rad1 -> rad2 -> "Y" to GPU 1 and 2 -> back to res

in your description, you run the water thru the radiator before it goes back in the reservoir. That should keep the water in the reservoir to be somewhat cool. In the end, there's no configuration where you have 1 connecting point between two loops where there won't be this kind of worry. If you want to use a Y and double up your loop, do it and see if the temps are acceptable for you.

This is what I have currently. Pardon my dust...

http://lh3.ggpht.com/_WBPepohOTqI/S9...2/IMG_1481.JPG

http://lh4.ggpht.com/_WBPepohOTqI/S9...0/IMG_1484.JPG

http://lh3.ggpht.com/_WBPepohOTqI/S9...0/IMG_1483.JPG

You don't want the heat generated by your cards bleeding heat over onto your CPU, or the other way around...

Instead of...
Res => Pump =>CPU => 8800GTX => 8800GTX => Rad 120.3 => Rad 120.2 =>Res.

Do this...
Res => Pump => CPU => Rad 120.3 => 8800GTX => 8800GTX => Rad 120.2 => Res.

Running it through two Rads back to back isn't going to bring your liquid temps down below ambient, and you only need 1 rad to get the temps down close to ambient.

Biggest thing you need to do is develop a wire management strategy. You've got quite a birds nest, and cleaning that up will help out a lot.
I think running a "Y" anywhere in a system is a bad idea personally. If the objective is to keep flow at a constant rate so that each CPU/GPU receives adequate "blood flow" to "carry away the heat" then you're being counter productive by lowering the flow over your GPU's with a "Y"

I'm using 1/2" ID tubes with 3/4"OD. It'll be 1 tube going UP + 1 down + 1UP = 3 Tubes hanging!!! Wow!! Is that practically feasible? Can 1 pump handle all that?

Someone also told me I should consider water blocks on motherboard as well!!

The only benefit you get by adding a second loop (assuming you are using the same amount of rads) is a higher flow rate for each component. However this can be had by adding a second pump to your single loop.

In the end, you will still be adding the exact same amount of heat into your loop and dissipating the exact same amount of heat out from your loop. If you are worried about a component "heating" your loop, you can stagger rads throughout your loop if possible. If not, its not that big of a deal.

The only reason I can see someone needing a second loop, is if the want a smaller tube for their "secondary" components (ie chipsets, memory, mosfets).

Quote:

---

Originally Posted by StAndrew

The only reason I can see someone needing a second loop, is if the want a smaller tube for their "secondary" components (ie chipsets, memory, mosfets).

---

I can see your argument with your rig. Like my rig a long time ago. Now? The i7 and the new hot GPUs? Some new GPUs put out more heat than your whole system. New ballgame.

Almost have to in some cases.

Quote:

---

Originally Posted by StAndrew

The only benefit you get by adding a second loop (assuming you are using the same amount of rads) is a higher flow rate for each component. However this can be had by adding a second pump to your single loop.

---

I disagree. To clarify by "second loop" we're talking two totally independent water cooling systems pulling heat from the same box... just attached to different components.

If one loop is dedicated to just your CPU then your fans and radiator aren't having to deal with dissipating the extra heat that would exist in a loop with two video cards. GPUs run much hotter than CPUs, so this is actually injecting a huge amount of heat into the loop that will make your CPU run hotter.

Similarly, if one loop is dedicated to just your GPUs then you're getting some heat segregation there that will keep your components (especially your CPU) cooler.

Quote:

---

Originally Posted by Lucretius

I disagree. To clarify by "second loop" we're talking two totally independent water cooling systems pulling heat from the same box... just attached to different components.

If one loop is dedicated to just your CPU then your fans and radiator aren't having to deal with dissipating the extra heat that would exist in a loop with two video cards. GPUs run much hotter than CPUs, so this is actually injecting a huge amount of heat into the loop that will make your CPU run hotter.

Similarly, if one loop is dedicated to just your GPUs then you're getting some heat segregation there that will keep your components (especially your CPU) cooler.

---

but then at the same time wouldn't you be adding cooler water from the cooler component loops to the hotter loop and create an equilibrium ?

Quote:

---

Originally Posted by orson

but then at the same time wouldn't you be adding cooler water from the cooler component loops to the hotter loop and create an equilibrium ?

---

No, because there would be complete physical separation.
2 pumps
2 loops
2 rads
2 tanks
1 loop with GPU(s)
1 loop with CPU(s)

Would 1 tank be OK rather? I don't have room for 2 Res!

shunail: there are even 1x5.25 bay reservoirs for dual loops(two mini reservoirs in one hausing), so i doubt size/room issue is not solvable.
Oh. And btw, there can be loop setups without any reservoir at all (with T-line for filling). Just that it takes longer and is major PITA to fill it that way. Reservoir really eases initial filling.

2 single loops don't add additional heat to each other if setup to pull outside air. I get higher temps on all components with three 120.3 in a single loop, rather than using two 120.2 for CPU loop and a separate 120.2 rad for the GPU loop. By outside air, I mean air outside of the case. If you are pushing air in with loop 1 and pulling air out with loop2, then that would negate the separate loop thing since the heat is added back again after it's exchanged with the air in your case.

So here's what I've decided

XSPC Acrylic Dual 5.25in. Reservoir for Two Laing DDC with 2 Pumps conencted =RES+PUMPs
RES+pump 1 => CPU => MofSet => NB/SB => Rad 120.3 => Res
RES+Pump2 => GPU1 => GPU2 => Rad 120.2 => Res

2 seperate loops

Put the cpu on its own loop. The motherboard waterblocks will restrict flow and add heat to your cpu loop and it will make a difference to your cpu overclock and temps. If you put the mb blocks in with your GPU loop youll see better results. GPUs are more resistant to warmer water and deal way better with lower flow.

Personally I just run one big loop set out exactly as Lucretius suggested. I have my gfx blocks in paralell to reduce flow restriction and use a single EK 4.0 pump.

Quote:

---

Originally Posted by Conumdrum

I can see your argument with your rig. Like my rig a long time ago. Now? The i7 and the new hot GPUs? Some new GPUs put out more heat than your whole system. New ballgame.

Almost have to in some cases.

---

My Q6600 with almost 1.5V at 3600 gets quite toasty (maybe not as much as the i7). And my three 9800's with ~1.6V, 900+ core, and 2300 shader gets hotter than most newer GPUs.

Quote:

---

Originally Posted by Lucretius

I disagree. To clarify by "second loop" we're talking two totally independent water cooling systems pulling heat from the same box... just attached to different components.

If one loop is dedicated to just your CPU then your fans and radiator aren't having to deal with dissipating the extra heat that would exist in a loop with two video cards. GPUs run much hotter than CPUs, so this is actually injecting a huge amount of heat into the loop that will make your CPU run hotter.

Similarly, if one loop is dedicated to just your GPUs then you're getting some heat segregation there that will keep your components (especially your CPU) cooler.

---

You cant create or destroy energy. Making a second loop does not make your heat magically go away.

If you have a CPU that dissipates 200Watts of heat and three GPUs that dissipate 100 watts each, regardless of how many loops you have, your total heat input is still 500Watts. And if you assume the same amount of rads, the amount of heat dissipated is also the same, no matter how you cut it. And dont forget, radiators are more efficient the hotter the water is.

By making a second loop, you are adding to the over all resistance by increasing the overall tube length. This is overcome by the fact that you now have two pumps, but it will be more beneficial to just add a second pump to your single loop, keeping you tube length (and therefore resistance) better optimized.

When setting up a loop, first install the pump and reservoir followed by the rads and blocks as best as you can. Then plan out the most direct path for your tubes, avoiding un-necessary bends, loops, etc... If you are worried about heated water from your CPU affecting your GPUs, its pretty easy to put a red between then (most cases/moboards can internally fit a 120mm rad on the 120mm exhaust). If you are able to stagger the rads just right, and have a radiator that dissipates 200+Watts between your CPU and GPU's (and a 300+watt rad after your GPUs), then you just isolated your GPUs and CPUs thermally (just like you had two loops; but better).

If you dont have an efficient set of radiators (ie, the amount of heat input is equal to or greater than the ability of the radiator to dissipate efficiently) making two loops you can optimize the performance of one of your components at the price of degrading the cooling on the other. However this is stupid as for the same price of a new pump, res, and tubing, you can probably just get a new radiator.

Dont fall for the 2 loop nonsense.

Quote:

---

Originally Posted by StAndrew

Dont fall for the 2 loop nonsense.

---

I respectfully disagree.

Using your example, two 500w rads used in separate loops should cool better than two in series in a single loop. Because the practicality is that most people will need a lower CPU temperature than GPU. And I think even a 1c increase in temperatures added from your GPU would be worse than nothing added at all. In reality it is pretty hard to measure exact heat dump, that's why we all have huge oversized rads... Correct me if I'm wrong, that's just how I understand it.

Add a second pump to the single loop and compare. Otherwise you are comparing apples to oranges.

Realize, depending on how you split up the loop, one component may be cooled better, but at the expense of the others. Its physically impossible for both components to be cooled better if you keep the other variables exactly the same. Its the laws of thermodynamics.

I'm more confused than before!!! :(

Quote:

---

Originally Posted by StAndrew

Add a second pump to the single loop and compare. Otherwise you are comparing apples to oranges.

Realize, depending on how you split up the loop, one component may be cooled better, but at the expense of the others. Its physically impossible for both components to be cooled better if you keep the other variables exactly the same. Its the laws of thermodynamics.

---

i'm no expert (and plan on running a single loop anyway), but i think most of the '2 loop' people are advocating exactly that...you're cooling the CPU better at the expense of the GPUs, because collective opinion is that GPUs are not as temperature sensitive (though why that should be I have no idea). perhaps it's because GPUs are already running very close to the ragged edge, whereas CPUs (eg current i5/7s) are, at stock levels, running vastly underclocked and undervolted compared to their limits, and are thus 'undercooled' as well. when you start o/cing up to the limits, then you need a more extreme cooling solution to match.

2 loops is absolutely NOT nonsense! Two loops is about heat distribution.

The reason for using two loops (usually CPU loop and GPU/MB loop) is to get better performance for the CPU (and because we can :D).

It is true that if both loops have the exact same rad+fan e.g. each loop has a triple rad with 3 fans, and the CPU and the GPU(s) generate an equivalent amount of heat, then the difference will be small and mostly due to flow. However, if your GPU(s) generate a lot more heat than your CPU, then 2 loops make absolute sense.

GPUs are designed to run much hotter than CPU and generally their O/C potential is not that great. Most people watercool their GPU less for O/C than for reduced noise.

So to answer your question, if you are going to use the exact same type of rad and fans for both loops and if both your CPU and GPU generate an equivalent amount of heat, you probably won't see much of a difference. Otherwise, split your loop (and add a separate reservoir), your CPU will have better temperature and your GPUs won't mind :yepp:

EDIT: @facboy, exactly!

Quote:

---

Originally Posted by Hannibal Lecter

2 loops is absolutely NOT nonsense! Two loops is about heat distribution.

The reason for using two loops (usually CPU loop and GPU/MB loop) is to get better performance for the CPU (and because we can :D).

It is true that if both loops have the exact same rad+fan e.g. each loop has a triple rad with 3 fans, and the CPU and the GPU(s) generate an equivalent amount of heat, then the difference will be small and mostly due to flow. However, if your GPU(s) generate a lot more heat than your CPU, then 2 loops make absolute sense.

GPUs are designed to run much hotter than CPU and generally their O/C potential is not that great. Most people watercool their GPU less for O/C than for reduced noise.

So to answer your question, if you are going to use the exact same type of rad and fans for both loops and if both your CPU and GPU generate an equivalent amount of heat, you probably won't see much of a difference. Otherwise, split your loop (and add a separate reservoir), your CPU will have better temperature and your GPUs won't mind :yepp:

EDIT: @facboy, exactly!

---

I guess I see your point. However, I like to keep it simple. Making two loops is not cost effective when compared to making one properly optimized loop. Its very easy to thermally isolate your components with the proper radiators while maintaining a single loop. In your case, you are describing a loop that is not properly optimized as far a heat load and radiator capacity is concerned, which IMHO is nonsence. Just my :2cents:.

Now, should I run N/B & S/B and GPU one loop and MOFSet and CPU in another loop??
Or MOFset, N/B, S/B & CPU one loop and GPU another?
Or Complete Board's blocks and GPU and CPU on its own.

I'm not looking for O/C at all! Just need system running smooth without getting hot