Dual loop compared to 2 pumps in series versus 2 pumps in parallel
Dual loop compared to 2 pumps in series versus 2 pumps in parallel
I'm exploring my fourth custom water cooling project and am considering using two matched D5 pump/res combos—one from an old build and one new. I'm curious about combining them into one system. Should I run them in series, parallel, or set up a dual CPU/GPU loop?
I tested a single D5 for more than six years and it continues to function properly. Many people seem to overlook the impact of pumps failing. Also, your PC will likely shut down when temperatures hit their limit, so it shouldn’t cause any damage.
You can use either two pumps in series or parallel, depending on your needs and future plans. Do you have any intention of expanding the loop later? The main drawback of a dual-loop setup is managing two separate hardware sets, but if space allows, you’re free to proceed. Water cooling gives you flexibility in configuration, as long as flow isn’t too restricted or completely blocked—those are the main concerns.
I'm drawing from automotive expertise, this should apply. When using two pumps in series—even different ones—the flow improvement tends to be nearly proportional. I find it surprising but logical. This suggests it's usually preferable to run them in series since if one fails, the other keeps working. It ensures your system remains functional even with a single component malfunction. With separate loops, a failure of one pump can shut down the whole setup until repaired.
I tested a single D5 for more than six years and it continues to function properly. Many people seem to overlook the impact of pumps failing. Also, your PC will likely shut down when temperatures hit their limit, so it shouldn’t cause any damage.
You can use either two pumps in series or parallel, depending on your needs and future plans. Do you have any intention of expanding the loop later? The main drawback of a dual-loop setup is managing two separate hardware sets, but if space allows, you’re free to proceed. Water cooling gives you flexibility in configuration, as long as flow isn’t too restricted or completely blocked—those scenarios are problematic.
Thanks for the update. I'm considering whether a parallel pump loop would be appropriate in this setup. Any insights you can offer would be greatly appreciated.
Correct your understanding: a series loop increases head pressure for the same flow rate, while a parallel loop raises the flow rate without changing the head pressure.
I've recently completed my fourth custom water cooling project and am now considering two matched D5 pump/res combos. One is from a disassembled build, the other is brand new. I'm curious about the best approach to combine them into one system. Should I run them in series, parallel, or set up a dual CPU/GPU loop? You mentioned thinking about keeping the second as a backup—since you experienced a D5 failure last year after four years of use, but managed to replace two units for redundancy. It seems you already have some contingency plans in place.
Yes, but a single loop remains overall, functioning as a series. You could have splits to supply the parallel parts of the loop, yet ultimately those splits reconnect into one continuous, serial section of the loop. A parallel split reduces restriction and, depending on its placement, may allow quicker flows for certain sections if pumps are positioned after the split instead of before. However, you must also consider feeding two D5 pumps each with a 1/2"ID inlet using just a single 1/2"ID tube, meaning your feeding capacity is effectively cut in half. This reduction still applies to the serial segment of the loop, which remains more restrictive overall.
This is my fourth custom water cooling project, and for the first time I’m using two matched D5 pump/res combos. One from a disassembled build and one brand new. I only need one, but it looks great having two pumps next to each other. I’m wondering which setup would work best—whether to run them in series, parallel, or a dual CPU/GPU loop. Have you thought about keeping the second one as a backup? I had a D5 failure last year after four years of use, but since I already bought two D5s for redundancy, I’m back up quickly. In your case, you likely already have a backup ready to go.
Thanks Ryan, this is something I’ve been thinking about too. Honestly, the flow rate and pressure from one D5 should be more than enough for this loop. But placing two reservoirs side by side looks really nice. It might make more sense to run two standalone reservoirs and install a single pump in a separate spot. Buying two reservoirs and a single pump top wouldn’t cost much, and I’d have spare parts for future upgrades.
Alternatively, having two pumps—either in series or parallel—would be convenient and feasible with the equipment I already own.