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Hey Everyone,


I am new to water cooling and am trying to plan out a new build.


My question is if it is possible to use 2 pumps on Hydro X, I was thinking of doing 2 loops in the system. My thought process is to have 2 higher flow rates to keep temperatures even lower.


Pump -> CPU -> Radiator -> Pump

Pump -> GPU -> Radiator -> Pump


I also see a lot of people go:


Pump -> GPU -> CPU -> Radiator -> Radiator -> Pump


Would it not make more sense to go:


Pump -> GPU -> Radiator -> CPU -> Radiator -> Pump


In my mind that keeps it cooler? Again I am new to this so I am just throwing out ideas, any feedback is much appreciated!

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Loop order doesn't make much difference in most scenarios. The radiator can only reduce the coolant temperature by 1-2C on each pass, so the difference to the next component by going GPU-> CPU -> Radiator versus GPU-> Radiator-> CPU will also be the same 1-2C. A water cooled GPU typically runs 35-50C, so no one cares about 1-2C there. It really only has meaning if you are pushing the CPU to the absolute limit where 1-2C might matter or if you have multiple GPUs prior to the CPU. In reality, the requirements for setting up the physical system usually dictate where things go and in what order. Nobody wants tubes zig-zagging across their case. Many end up with Res/Pump-> GPU -> etc. because of the pump's location and easy proximity to the GPU inlet versus trying to bypass the physical card to reach the CPU. It can be done any way, but the layout and angles usually force one way or another.


You certainly could set-up a dual loop system. The advantage is most present when using a large watt GPU and a comparatively small watt CPU (like any 75-95W TDP model). At 300W+, large GPU models have a much heavier impact on coolant temperature than most any normal CPU. The CPU shares the coolant stream in a single loop and coolant temperature is minimum CPU or GPU temp. In effect, if the GPU makes the coolant 10C warmer, then the CPU temp is raised by the same amount at all load levels.


Most people only wind up with dual loops in really large systems (physical case size or number of components). You haven't mentioned what hardware or case you are going to be working with, but my suggestion is this. If you really want to do a dual system based on principle, you put the CPU on an AIO cooler and the GPU on the custom loop. This separates the systems. I ran this way for quite a while with both 5930K and 8700K systems, plus a Titan X(P) and later 2080 Ti. The CPU radiator would keep icy cool at 3-4C above room temp at load. The 280mm radiator on the GPU would let it get up to 38-40C coolant temp, but that heat was dumped directly out of the case. If you are trying to maximize cooling for both components in a medium sized case, this likely works better. Of course, if you have the space, you certainly can do dual custom loops. There are a few cases that come to mind that almost demand it because of the layout.

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Thank you so much for taking the time to write such a lengthy response. I will probably stick to 1 pump and run gpu -> cpu since we are talking about a small difference.


As for what I am planning in terms of HW, I want to get my hands on a 3950x, Gigabyte Aorus Master x570, 32gb (2x16) 3600Mhz 16cas, lian li o11 dynamic xl and am currently debating if I should wait for a potential 3080 ti in June-ish or just go for the 2080 ti. This seems to be the never ending question when building pc's, wait or build now since there is always something on the horizon.

Edited by Seth772
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You are most likely looking at 2x360mm radiator system with flexible placement choices at 2 of the three locations. I don't see a lot of reason to run a dual system for what you have selected and while possible, it might look a bit cramped in the XL and require a distro block or other unconventional pump/reservoir.


My typical max wattage for 8700K +2080 Ti is 500W and 2x360 keeps me at around a 9-10C coolant rise. That would be a reasonable expectation for the combo above.

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  • 5 months later...

Hi there, I, also new to custom cooling and was looking at the Hydro X system. I have a question that is very similar to @Seth772

Can I run two separate loops with one pump? One for the CPU and the other for the GPU.

It's a three radiator configuration and I would have both loops intersect at the third radiator using a Y or T fitting before flowing back into the reservoir. *

Here is the configuration I'm interested in from the corsair website:



I don't know if all 3 ports on the bottom of the XD5 pump out flow? I'd like one for a ball valve drain and the other two for the configuration I'm interested in doing.

CPU Loop:


Res. -> 360/54mm radiator(1) -> CPU -> 360/30mm Return Radiator(3) -> Res.


GPU Loop:


Res. -> 360/54mm radiator(2) -> GPU -> 360/30mm Return Radiator(3) -> Res.


According to Corsair the XD5 pump can handle this task no problem but it's the two loops that intersect at the return that I'm unsure about. I'm not sure if either of you

@c-attack @Seth772 have the answer but I would much appreciate any advice or guidance from someone more experienced than myself.


The build I'm planning is also similar to @Seth772 but I have two in mind. I already have the O11 Dynamic XL case



Thread Ripper 3960x

ASUS ROG Zenith II Extreme

128GB G.SKILL Trident Z Neo 3600 (8x16GB) 16cas

3000 series PGU


Secondary build:

Baby Thread Ripper 3950x

Gigabite X570 Aorus Xtreme128GB G.SKILL Trident Z Neo 128GB G.SKILL Trident Z Neo 3600 (4x32GB) 18cas

3000 series PGU

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the problem i can see is that you may have trouble with flow distribution between CPU and GPU.

Usually manufacturers try to have their cooling block be roughly the same restriction so that flow is equally shared between blocks.

here you basically make a parallel loop with separated radiators (and varying tubing lengths/bends) so it will be hard to predict if you will have enough flow on both sides or if one will take most of it and let the other end overheat.


To be honest, you'd be better off simplifying the loop with a "normal" parallel loop :


Pump - CPU and GPU inlet - CPU and GPU outlet - 360 rad - 360 Rad - 360 rad - Pump


You'll have less pipework, hence less restriction to flow, and 3x360 rads will still be overkill for the amount of heat either systems will put out

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I had to re-read a few times to make sure I understand, so if I don't have this right, please say so.


I can't think of a good reason to branch the loops off. Unlike two distinctly separate systems where each which has its own temperature, your loops will combine back at rad 3 and return the CPU and GPU at the same temp. In return, you open the door for weird flow problems where the tubes come back together and I can't really predict what might happen. However, even if everything does go perfectly, I don't see the performance advantage over a in-line series of blocks and radiators.


Loop order generally does not matter. However, once you get into the 3 radiators or another situation where one radiator must dump heat into the other(s), there may be a preference. You'd like to dump as much heat as possible after the CPU/GPU before it comes back around to the intake radiator. Theoretical example: pump -> CPU -> GPU -> rad 1->2->3. Coolant temp comes out of the GPU at 35C. Radiator 1 drops that by 1.5C, then another 1.5C at #2, and then by the time it get to radiator 3 you are down to 32C. This means radiator 3 has the coolest exhaust temperature and that is the one you want as the intake radiator. This keeps the air pushed into the case cooler than the coolant temp in the radiators that are exhausting. This is necessary for the cooling effect. If you blow 35C air at a 32C radiator, it won't stay 32C for very long before warming up.


To be clear, all possible flow routes work and we are not talking about ineffective cooling. This is maximizing all possible gain for the highest efficiency so you can scrape back 2C from something. The realities of hardware size and tube routes may force things another direction. Perhaps using bottom and side intake rads and the top as exhaust is just as efficient as model I proposed. If you are not in a hurry, I'll let you know soon. I am working on this now, just finishing up a few weeks of 2 radiator testing in the XL. I'll be moving onto three radiator testing soon, but based on comparing my results to others, the expectation is about 2C less with radiator number 3.

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Opening a window has more impact than loop order :P


Since you're new to it, for a first loop i'd stick to the kiss principle.. Keep It Stupid Simple.

2 blocks, 3 rads, all in series. then play from there. fittings are expensive, you may find out later that adding more of it to gain half a degree may not have been worth it (but would sure look good).



My experience :

started with 2x 280 rads on a series loop on a corsair 680x. later moved to a O11XL with the same setup..

I added a 360 to the loop while going parallel on CPU and GPU.

Finally switched the bottom intake 280 for a 360.


All in all i always ended up, give or take one degree, with the same coolant temperatures.

The only thing that made it vary by a lot was the glass panels of the 680X (dropped by 4 to 6° by removing them).


TLDR : maybe, save on fittings to invest on a case with good airflow. That will have a bigger impact

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