Clarification on GPU / CPU flow

[Captain Matt]

I have an idea for a loop as roughly diagrammed in my attached image but I'm not sure it will work.

 

When I search things like, "how to route watercooling loop gpu" no video explains how this works...

 

Would the loop I diagrammed in my attached image work? If yes, why?

 

Would the outlet from the CPU be flowing into the outlet of the GPU and so it all flows correctly? That's my understanding.

 

Examples using what I believe to be this arrangement:

• Reddit Example
• EKWB Example

 

 

Don't worry about the routing. I know the PSU may be in the way of this design.

[For Science!]

9 minutes ago, Captain Matt said:

I have an idea for a loop as roughly diagrammed in my attached image but I'm not sure it will work.

 

When I search things like, "how to route watercooling loop gpu" no video explains how this works...

 

Would the loop I diagrammed in my attached image work? If yes, why?

 

Would the outlet from the CPU be flowing into the outlet of the GPU and so it all flows correctly? That's my understanding.

 

Examples using what I believe to be this arrangement:

• Reddit Example
• EKWB Example

 

 

Don't worry about the routing. I know the PSU may be in the way of this design.

 

This is known as parallel flow, it works. Think about a garden sprinkler, the water flow splits on the inlet, and merges again in the outlet.

[RONOTHAN##]

Yeah, that's fine. Just make sure that the inlet and outlet are on the same sides, and you should be good. Parallel (what that orientation is called) optimizes for higher water flow at the expense of more fittings. Sequential (one part to another) is cheaper since it requires less fittings, but lowers water flow. Performance difference is negligible between the two, and it's basically whether you think it looks better enough to justify the extra $20-30 in fittings. 

[Captain Matt]

2 hours ago, RONOTHAN## said:

Yeah, that's fine. Just make sure that the inlet and outlet are on the same sides, and you should be good. Parallel (what that orientation is called) optimizes for higher water flow at the expense of more fittings. Sequential (one part to another) is cheaper since it requires less fittings, but lowers water flow. Performance difference is negligible between the two, and it's basically whether you think it looks better enough to justify the extra $20-30 in fittings. 

Thank you!

[fonzz1e]

hmmm... don't parallel flow only works when waterblocks restriction are similar? 

 

 

[Captain Matt]

On 1/21/2022 at 9:58 PM, fonzz1e said:

hmmm... don't parallel flow only works when waterblocks restriction are similar? 

 

 

Great point. I'll watch for that.

[For Science!]

On 1/22/2022 at 5:58 AM, fonzz1e said:

hmmm... don't parallel flow only works when waterblocks restriction are similar? 

 

 

to get a equal flow, yes. But honestly even if the flow was split 1:9, there would still be enough flow with a D5/DDC pump.

[Captain Matt]

23 minutes ago, For Science! said:

to get a equal flow, yes. But honestly even if the flow was split 1:9, there would still be enough flow with a D5/DDC pump.

That's what I was thinking.

 

It's been tested a bunch of times that flow order doesn't matter. So whether I ran these two right together or somewhere else in the loop, the TOTAL resistance in the loop is still the same.

[For Science!]

5 minutes ago, Captain Matt said:

That's what I was thinking.

 

It's been tested a bunch of times that flow order doesn't matter. So whether I ran these two right together or somewhere else in the loop, the TOTAL resistance in the loop is still the same.

this is more a question of flow rate within the block, but yes, flow rate also does not matter so much in the broader scheme of liquid cooling. So if you like the look of the parallel loop go for it  

[thrasher_565]

11 hours ago, For Science! said:

this is more a question of flow rate within the block, but yes, flow rate also does not matter so much in the broader scheme of liquid cooling. So if you like the look of the parallel loop go for it  

well to a point. every 1lph flow rate you get about 1 degree drop. i be leave a d5 is around the 2. something lph.  ddc is lower.

 

is it worth spending the moeny to make it faster not really

Edited January 24, 2022 by thrasher_565

[For Science!]

2 hours ago, thrasher_565 said:

well to a point. every 1lph flow rate you get about 1 degree drop. i be leave a d5 is around the 2. something lph.  ddc is lower.

 

is it worth spending the moeny to make it faster not really

sorry, your math definitely does not check out.

 

1 Gallon per minute (a not unusual flowrate) = 227 liters per hour

0.5 Gallon per minute (also not an unusual flowrate) = 113.5 liters per hour

 

you do not get a 113.5 degree drop or increase going from 0.5 gpm to 1 gpm.

 

Perhaps you meant gpm instead of lph, which in that case it may be about right.

[bowrilla]

On 1/21/2022 at 2:48 AM, RONOTHAN## said:

Yeah, that's fine. Just make sure that the inlet and outlet are on the same sides, and you should be good. Parallel (what that orientation is called) optimizes for higher water flow at the expense of more fittings. Sequential (one part to another) is cheaper since it requires less fittings, but lowers water flow. Performance difference is negligible between the two, and it's basically whether you think it looks better enough to justify the extra $20-30 in fittings. 

Maybe I'm getting your point wrong but parallel flow will reduce flow rate, serial flow is better for higher flow. Not that it matters much. With parallel flow you have basically a flow divider, if both blocks and loop runs have exactly the same restriction, the flow is divided 50:50. So assuming an overall flowrate of 1gpm, both CPU and GPU block will have 0.5gpm.

 

Within reason flow doesn't matter so it's not that much relevant after all. There's basically nothing significantly to be gained above 0.5gpm or even 0.25gpm. 1-2K difference in your coolant temps won't significantly impact your system's performance. Whatever difference you'd see in benchmarks is probably more margin of error than real world performance impact.

[thrasher_565]

 

however some gpu and cpu blocks have a inlet and outlet and be going backwards can reduce the cooling buy like 3 to 5 degrees...

Edited January 24, 2022 by thrasher_565

[bowrilla]

43 minutes ago, thrasher_565 said:

 

however some gpu and cpu blocks have a inlet and outlet and be going backwards can reduce the cooling buy like 3 to 5 degrees...

Do you imply with that image that serial loops will run hotter? Because that's not really a thing. I mean, slightly higher coolant temps would decrease dT between coolant and block reducing heat transfer efficiency and therefore resulting in a little less heat energy being transferred. The difference would be marginal and barely measurable with sensors commonly available to watercooling enthusiasts. Basically: the amount of heat energy being induced into the system will not change in any significant way. By reducing the flow rate the volume of coolant over time will obviously decrease while the amount of heat energy being induced through the block into the coolant stays the same. Therefore the outlet temps will be just about the same.

[For Science!]

flow is split in a parallel flow, but it is less restrictive than two blocks in serial and thus will have a higher flow rate (in the entire loop) than in serial mode.

https://www.ekwb.com/blog/does-loop-order-matter/

[bowrilla]

53 minutes ago, For Science! said:

flow is split in a parallel flow, but it is less restrictive than two blocks in serial and thus will have a higher flow rate (in the entire loop) than in serial mode.

https://www.ekwb.com/blog/does-loop-order-matter/

Ah, total flow. Yes, that is plausible. 

[thrasher_565]

5 hours ago, bowrilla said:

Ah, total flow. Yes, that is plausible. 

there are different ways of getting lower temps. flow speed is one of them. more surface area is another. push pull is another way.

[Captain Matt]

1 hour ago, thrasher_565 said:

there are different ways of getting lower temps. flow speed is one of them. more surface area is another. push pull is another way.

Or...

 

FAN GO BRRRRRRRRRRRRRRRRRRRRRRRRRTTTTTTTTTTTTT

[thrasher_565]

3 hours ago, Captain Matt said:

Or...

 

FAN GO BRRRRRRRRRRRRRRRRRRRRRRRRRTTTTTTTTTTTTT

oh ya that too faster fans... lower temps