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Series or Parallel?

B

Bionic_Tuna

Weaksauce
Joined
May 1, 2003
Messages
70
When cooling a GPU and CPU, is it best to just do a series, with CPU out going to GPU in, or Y split it from the radiator and go separately to CPU and GPU, then back together to the res?
 
Bionic_Tuna said:
When cooling a GPU and CPU, is it best to just do a series, with CPU out going to GPU in, or Y split it from the radiator and go separately to CPU and GPU, then back together to the res?
Click to expand...

It seems to me that the parallel setup would get the coolest water to your GPU, but I'm not sure if there are any downsides to this strategy. I'm sure a more knowledgeable watercooler will be able to field that question better than I.
 
You would have to make sure that there would be enough water going to each block. If one of the blocks was pretty restrictive, and the other was free-flowing, then the restrictive one wouldn't get any water (barely any). Water works like electricity here, it moves along the path of least resistance. You would have to put in restricting valves to control the flow.

I've read on here that the temperature difference before and after a block is very small (since there's so much moving through the blocks), so there seems to be no point to a parallel setup here. The slight difference in water temps to the GPU doesn't seem to be worth the hassle. Besides, you would actually be pushing less water past each block, potentially lowering their cooling effectiveness. ;)
 
Don't forget that like electricity, with a GPU in series will make there be less flow through the system as well. So it depends on how balanced the two coolers are... if they are about the same I'd say go parrallel and get higher total flow unless the most restrictive element is your radiator by far. It really depends on your system and components.

Either way, you're looking at reduced flow through your CPU block.
 
RickyJ said:
You would have to make sure that there would be enough water going to each block. If one of the blocks was pretty restrictive, and the other was free-flowing, then the restrictive one wouldn't get any water (barely any). Water works like electricity here, it moves along the path of least resistance. You would have to put in restricting valves to control the flow.

I've read on here that the temperature difference before and after a block is very small (since there's so much moving through the blocks), so there seems to be no point to a parallel setup here. The slight difference in water temps to the GPU doesn't seem to be worth the hassle. Besides, you would actually be pushing less water past each block, potentially lowering their cooling effectiveness. ;)
Click to expand...

This is absolutely correct. I went and forgot my intro circuits class. I'll now go hang my head in shame. :(
 
Good question, since I'm at the same point in my set-up and not sure were to go yet. A lot I think depends on your pump. Mine (Eheim 1250) provides around 5 gpm. My block (DD tbx) lets about 3 gpm through, the gpu block (DDMaze4) is reported to be around 2 gpm. So I guess I try parallel first. I grabbed some Dwyer flow meters from Ebay to monitor the split, and adjust it if necessary.
 
TheArchitect said:
Don't forget that like electricity, with a GPU in series will make there be less flow through the system as well. So it depends on how balanced the two coolers are... if they are about the same I'd say go parrallel and get higher total flow unless the most restrictive element is your radiator by far. It really depends on your system and components.

Either way, you're looking at reduced flow through your CPU block.
Click to expand...

Yes, matching is VERY important here. It also depends on the head vs flow characteristics of the pump you're using.

Running them in parallel will be like running resistors in parallel: pressure (voltage) will be the same on both lines, so the flow (current) depends entirely on the restriction from the blocks.

In the parallel system (with matched blocks), the system restriction from the blocks will be halved. This does not necessarily mean twice the system flow, since it depends on your pump characteristics.

Once you go parallel, things get a bit more complicated. I was looking at this route when I was planning on making my blocks (have the copper already), but decided that the added restriction from balance valves and such would outweigh any gains in my planned system.
 
I would run them in series, too much resistance is bad, + it has to go back to the Pump through the same sized tube, so it's not going to push as much pressure or water through ewach of the blocks? Unless your going to use 2 smaller tubes and use blocks with similar flow , then connect them to a tube 2x as large for their return, and have a higher pressure pump, I would stick to series.....
 
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