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Discussion Starter · #1 ·
I hope someone can put to rest a couple of questions I have about manifolds in builds.

Current setup is Pump ::: CPU ::: GPU ::: MO-RA 3 Radiator ::: Pump

Plan is to add a second gpu to the loop in the future, but I can already see that cpu load has a ~4 degree impact on gpu temperatures, and am wondering once the second gpu is added just what kind of jump in temp it will see receiving heated coolant from both the cpu and gpu before it.

What EK's manifold has to offer is separate flow channels for the cpu(s) and gpus. My questions are: can this kind of setup be handled by a single D5 pump and will it provide the same cooling performance or better than just running the setup in series?
So again, can a single D5 pump handle this configuration: Pump ::: Manifold ::: ( ::: CPU / ::: GPU1 / ::: GPU2 ) ::: Manifold ::: MO-RA 3 Radiator ::: Pump and can I expect no cooling performance drop, especially for the cpu (given that the flow is split in two inside the manifold, provided am I am understanding manifolds and liquid flow correctly)?

A big thank you.
 

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What are the water temps and flow rate?

The temperature of the water should be constant
 

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Discussion Starter · #3 ·
What are the water temps and flow rate?

The temperature of the water should be constant
I do not know what the water temperature is in there current setup, but I can see GPU temps rise when CPU has load.
 

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I do not know what the water temperature is in there current setup, but I can see GPU temps rise when CPU has load.
Get a temp sensor for the water and look at adding a flow meter. CPU/GPU temps are dependent on the block and water temps. Want better temps then either cool the water better, hence the need for a temp sensor or buy better blocks, with diminishing returns
 

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I just had to pull the flow meter from my loop. The flow got too high after I rebuilt the loop to reduce restriction and it started rattling a lot (>400 lph). :(

For water temps, the idle GPU is usually ~2°C above the water in my experience. At least, very closely connected to the water temps. A temperature sensor is nice to have though, especially when the GPU is not idle. ;)
 

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Discussion Starter · #6 ·
What about flow&pressure when using such a manifold with just one pump? Will the flow decrease so much to the point where CPU temp will increase? The general impression is that CPU blocks are more restrictive. Since I can't attest I understand fluid dynamics enough, if the manifold splits flow in half and the CPU block is generally more restrictive can one conclude that the final flow rate to the CPU will be lass than <1/2 of the original flow rate?
 

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Since I can't attest I understand fluid dynamics enough, if the manifold splits flow in half and the CPU block is generally more restrictive can one conclude that the final flow rate to the CPU will be lass than <1/2 of the original flow rate?
Hopefully not quite that low, but probably close. The restriction is lower with a second path so the total flowrate should increase, but then more than half the flow goes through the GPU.

It is normal for the CPU temperature to increase when adding a GPU block in any configuration, unless you add another pump at the same time. In parallel or series there is less flow through the CPU block with a GPU block as part of the loop.
 

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Like Shawn said your whole loop is the same temperature. Those EK pro manifolds are for pro setups like this that use powerful pumps. When you have 6 x 3090s, the first one will be running much cooler than the last one if you hook them up in series.


A single D5 is not enough for a loop with 2 GPUs (presumably 3090s) and adequate radiator capacity for 2 GPUs, even without the manifold.
 

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Discussion Starter · #9 ·
Like Shawn said your whole loop is the same temperature. Those EK pro manifolds are for pro setups like this that use powerful pumps. When you have 6 x 3090s, the first one will be running much cooler than the last one if you hook them up in series.


A single D5 is not enough for a loop with 2 GPUs (presumably 3090s) and adequate radiator capacity for 2 GPUs, even without the manifold.
How does one determine when a D5 is not enough? Talking about on a per case, field conditions evaluation. I have a single D5 right now, a cpu block and a gpu block, and then a mo-ra 3 420 radiator. I don't yet have a flow meter but supposing I did, could that be enough to evaluate if the pump is enough?
 

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How does one determine when a D5 is not enough? Talking about on a per case, field conditions evaluation. I have a single D5 right now, a cpu block and a gpu block, and then a mo-ra 3 420 radiator. I don't yet have a flow meter but supposing I did, could that be enough to evaluate if the pump is enough?
Provided it is an accurate flow meter, and not something purely for aesthetics, that is exactly what you would use to make the determination.
 
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