Skip to content

Open Loop vs Closed Loop Liquid Cooling: A Complete Comparison

Liquid cooling has become an increasingly popular method for regulating component temperatures in high performance PCs. But enthusiasts choosing an optimal setup face a decision between open loop and closed loop systems, each with their own pros and cons. This expert guide will breakdown everything you need to know when deciding between open and closed loop liquid cooling.

What Are Open and Closed Loop Liquid Cooling Systems?

Open loop liquid cooling uses components chosen and assembled by the user to form a custom cooling loop. These include a pump, radiator, CPU block, fittings, tubing, coolant and more tailored to match your PC‘s thermal output.

Closed loop/AIO (all-in-one) liquid coolers are prebuilt, sealed units designed to simply mount to your CPU socket and radiator bracket. Popular models like the Corsair H100 offer plug-and-play installation and maintenance-free operation.

While both circulate liquid to pull heat away from components, open loop flexibility comes increased complexity compared to AIO convenience. We‘ll now do a deep dive on the key differences PC builders should consider.

Open Loop vs Closed Loop Cooling Comparison

  Open Loop Closed Loop/AIO
Complexity Highly customizable using separate components Prebuilt, fewer parts
Cooling efficiency Superior, tailored to thermal load Reliable "good enough" cooling
Maintenance Frequent – fluid, cleaning, leak checks Minimal, self-contained
Cost More expensive startup and maintenance Cheaper initial purchase
Aesthetics Fully customizable tubing runs, RGB Limited configuration
Flexibility Choose each component All-in-one package
Skill level Advanced, proper configuration key Beginner to intermediate

Diving Deeper on Key Considerations

Now that we‘ve covered the basics, let‘s do a deeper dive into some of the critical points enthusiasts should factor into their open vs closed loop decision making.

Open Loop Customization and Planning

The open nature of custom loop components means plenty of planning is required for optimal performance. All pieces must seamlessly fit together into a loop that meets cooling and flow rate needs. Key steps include:

Choosing a Pump

Pumps drive the cooling liquids movement through the loop. Power and flow levels vary widely:

  • Small 50 GPH range pumps for basic CPU-only loops
  • High head pressure models (7m+) handle dense radiator/block configurations
  • PWM variable speed control recommended for noise and efficiency

Selecting Radiator Size

Radiator thickness and fin configuration alters potential heat dissipation. Options include:

  • 30mm – Basic cooling needs
  • 45mm – Better cooling with moderate thickness
  • 60-80mm Extreme radiators for max heat capacity

High airflow fan mounting points also critical. 360mm and 420mm radiators enable push/pull fan doubling for cooling capacity boosts.

Fittings, Tubings and Accessories

Rigid acrylic tubing allows stunning showcase builds but demands expert bending skills. Flexible tubing trades looks for ease – advanced users may interchange materials at strategic points. Fittings bridge these connections sealing flow. Quick disconnects also speed maintenance.

Coolant Choices

Traditional ethylene glycol coolants work well, but specialty fluids boast antifungal and anti-corrosive enhancements. Some include dyes or change viscosity responses to better retain heat across temperature swings. Make sure to select reputable brands to avoid gunking or breakdown over time.

With the right components selected, builders must then meticulously plan tubing runs accounting for pump locations, optimal component cooling order, drain valves placement and more. Leak testing and bleeding air upon completion also requires patience. So while open loops offer total control, be ready to spend time engineering a balanced system.

Recommended Open Loop Planning Resources:

  • ExtremeRig‘s definitive Open Loop Guide Series – tutorials and explainers covering component selection, bending, workshop tips and more in detail from liquid cooling veteran LinuxGurus.
  • Reddit‘s /r/watercooling – Active owner community chatting on troubleshooting, upgrades and showcasing Sometimes you want fans right up on either side of the radiator to maximize airflow and cooling. This is called a push/pull configuration.
  •‘s Beginner Water Cooling Guide – GPU+CPU focused guide covering planning, basic component breakdowns and build walkthroughs.

So while open cooling setup carries complexity, sufficient planning and education helps enthusiasts select components meeting performance and aesthetic goals.

Maintaining Peak Performance Long Term

Once built according to precise specifications, open loop systems must be maintained to uphold cooling capacity and component health over time. Common tasks include:

Leak Checks – Catching small leaks early prevents disastrous spills onto expensive PC hardware. Regular inspections of all connections for dampness minimizes this risk.

Coolant Top Offs – Fluid can slowly permeate tubing materials over years or leak out undiscovered for periods allowing air introduction. Checking reservoir levels and adding fluid helps compensate.

Bleeding Air – Tiny air bubbles get trapped while bleeding the loop initially but may still find ways to enter over time. These air pockets impede cooling efficiency, so rerunning bleeding procedures keeps things free flowing.

Biocides – While modern coolants have anti-microbial additives as standard, microorganisms can still slowly build up in parts of loop over multi-year operation. Periodic deep cleaning with biocides may be recommended by manufacturers, especially in tubing sections seeing stagnant flow.

Similarly, dust build up on radiators, corrosion in blocks, pump failures or basic wear on rotating parts can occur as loops age past 3-5 years old. So ongoing effort maintains these systems – allowing their superior cooling to continue protecting expensive components well past a typical closed loop lifecycle.

benchmark area

You‘ll gain lots of insight from the water cooling experts at – here are some of their CPU cooling benchmarks showing open vs closed performance:


Key findings:

  • At stock speeds, high end air coolers match or outperform many 120-240mm AIOs
  • With moderate overclocks applied, 240-280mm AIO performance meets recommended thermal ceilings (90C) in all tests.
  • With extreme overclocks, custom loops allowing 480mm+ radiators and high water delta T outperform all AIOs, allowing stable 5Ghz+ operation

So while closed AIO usage definitely brings substantial cooling improvements vs air, those chasing every last MHz will need an open loop build. Custom loops also better tame component heat from GPUs, RAM and other sources in one integrated setup.

Water Cooling Advancements Expanding Closed Loop Capabilities

As liquid cooling exploded in popularity for home builds over the past decade, closed loop AIOs have rapidly improved thanks to R&D and economies of scale. These innovations narrow the performance gap to open systems rapidly. Notable developments include:

  • Cold Plate and Microchannel Improvements – Redesigning water block baseplates for increased surface area contact and thinner channels speeds heat transfer from the IHS to coolant. Copper remains top choice for conductivity to coolant.

  • 6th Generation Pump Advancements – Companies like Asetek now offer pump/waterblock combos with power improvements up to 10X over air cooling and increased reliability through stronger bearings, lubrication and vibration reduction

  • Programmable RGB Lighting – While less functional than the features above, addressable RGB lighting on pump blocks, fans and radiators allow closed loops to aesthetically keep pace with open-style showcase builds. These visuals even sync with other system lighting thanks to motherboard and proprietary software (Corsair iCUE, Asus Aura Sync, etc) integrations.

  • Higher Efficiency Radiators – Improved fin density, sizing optimization and airflow augmentations like push/pull fan capabilities help dissipate heat faster into the surrounding environment.

Together these engineering steps enable all-in-one closed cooling loops to come remarkably close to open systems, especially for typical users not pursuing irrational CPU speeds. Their plug-and-play nature also means giving far less ground on reliability and convenience despite innovations narrowing the performance gap significantly.

Aesthetics, Visual Flair and Case Modifications

Function is priority one for most extreme overclocking builds choosing liquid cooling solutions. But once sufficient performance is assured, aesthetics and visual flair differentiate showcase systems. Open loops hold advantages here as well.

Fully exposed runs of rigid tubing zigging cleanly around components make for stunning showpieces. Glass panels show the liquid in motion, while RGB-adorned pumps, blocks and fans highlight key points of interest. Users can run long RGB strips along acrylic tubing for diffuse glows if desired.

And modifications allow custom cooling to literally burst from the traditional confines of a PC case. External mounting of radiators or full runs of tubing out of the main system area demonstrate mastery over conventional build constraints.

Closed loops must hide themselves fully away for clean looks – the best scenarios have minimal tubing showing leading to and from the pump/waterblock combo. Prefilled coolant avoids maintenance but limits color personalization. And RGB lighting remains restricted to fans attached to radiators and some upgraded pump block designs.

So ready-made closed loops trade the artistry and visual pop for simplified installation. RGB every component is the price for open loop builder‘s choosing their own adventure.

Which Liquid Cooling Choice Is Right For You?

With all factors and options explored, we can summarize recommendations on selecting either open or closed liquid cooling:

For extreme computing needs – focused on maximum cooling potential, future upgrades, and enthusiast overclocking – open loop cooling is the way to go. The learning curve is the price for pushing thermal performance to the limits. Plan for proper ongoing maintenance as well. Custom loops also allow cooling GPUs, RAM and other components more easily compared to most AIOs.

For plug-and-play CPU cooling focused on simplicity over customization – closed loop AIOs deliver "set and forget" installation. Performance tames temperatures reliably across CPUs ranging from 65W Ryzen 5600X to 280W enthusiast grade Intel chips. Closed loop cooling now brings water cooling to novice builders on a budget.

Alternately combining both methods offers a best of both worlds approach in high end builds – closed cooling on a GPU and open loop just for the heat intensive CPU for example. Budget, temps and ambition guide whether open or closed makes the most sense.

With all the facts above this guide aims to distill key tradeoffs – allowing you to maximize both cooling and convenience when selecting liquid cooling. Let us know if any other questions arise when planning your system!

Liquid Cooling FAQs

Is liquid cooling worth it over air cooling?

Premium tower air coolers still compete closely with smaller (120-240mm) closed loop AIO coolers, especially at stock speeds instead of overclocked settings. Liquid cooling makes the most sense for users wanting to push their systems past 5 Ghz on modern CPUs or needing to tame heat from high end GPUs. For pure hobbyists, custom loops also enable aesthetically stunning showcases unattainable by traditional fans and heatsinks.

Do closed loop AIOs require refilling coolant over time?

Not for the vast majority of users. These sealed loops are designed to operate maintenance free for 3-5 years thanks to non-permeable tubing and corrosion resisting components. Some may slowly lose minor fluid volume internally but require no top offs from owners. Like a car radiator, set and forget!

How often should open cooling loops be drained and cleaned?

Consensus agrees flushing open loops with distilled water every 12-18 months helps clear any build up of plasticizer oils from tubing or growths within blocks and radiators that may impede flow or cooling. Replacing fluid also compensates for minor evaporative losses over this timeframe.

What tubing is best for custom cooling: rigid acrylic or flexible?

Rigid acrylic tubing delivers jaw dropping results for showcase builds but requires significant skill to heat, bend, and fit runs cleanly. Flexible options from reputable brands offer nearly invisible performance for more novice modders. Advanced users may swap materials at strategic visible or tricky routing portions for a best-of-both approach.

How can I identify and fix leaks in my custom loop?

Close visual inspection along every inch of tubing is critical – small moisture beads indicate cracks allowing fluid weepage. Clamps can sometimes mend minor tubing leaks temporarily while permanent replacements ship. Fittings leaks require immediate power down, drying, and reseating connections with fresh o-rings/threading tape before continuing. Keep paper towels handy!