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Choosing the Right AIO Cooler Size: 240mm vs 280mm vs 360mm vs 420mm (2000+ word edition)

All-in-one (AIO) liquid coolers can transform high-end gaming PCs by enabling beastly overclocks while taming thermals and cutting noise. But with so many radiator sizes available from 120mm up to massive 420mm triple 140mm models, selecting the right cooler for your build is key.

As a hardcore gamer and overclocking enthusiast, I’ve tested and built with every type of AIO imaginable in pursuit of max frames per second while still keeping my rig both stunning and silent. In this epic guide, we’ll go in-depth to see how different AIO sizes compare so you can pick the best liquid cooler for YOUR killer gaming build!

The Evolution of AIO Cooling

Closed-loop all-in-one liquid coolers have come a long way over the past decade. While exotic water cooling used to be an expensive niche reserved for competitive benchmarkers, AIOs now deliver incredible performance at mainstream price points.

It started off small – simple 120mm units with loud 70CFM fans that offered minimal gains over midrange air coolers. But rapid innovation quickly stepped things up…

First came dual 120mm 240mm rads. These started to show solid improvement, dropping CPU temperatures by up 10-15°C over the tower coolers popular at the time. This allowed some ambitious overclocking that simply wasn’t possible on air.

Next was a watershed moment – the arrival of bigger 280mm and giant 360mm “mega coolers” sporting quieter 140mm fans. NZXT shook up the market in 2013 with their original Kraken X60 driving this trend. Gamers rejoiced at the 1940s sedan sized units enabling decent overclocks with reasonable noise levels.

Today, we have a huge range of AIO options at all prices and sizes. Massive 420mm radiators composed of triple 140mm fans used to cost as much as a whole mid-range gaming PC! Now they can be had for less than $200 bucks.

We’re truly spoiled for choice when it comes to selecting a liquid cooler for our gaming rigs. But more size doesn’t always equal better performance as we’ll see…

(insert image of NZXT Kraken X60 here)
The NZXT Kraken X60 helped popularize 280mm and 360mm AIOs for gamers

Cold Plate & Contact Efficiency

Before we dive into radiator sizes, let’s quickly cover the critical cold plate component that makes direct contact with your precious processor.

Early AIO cold plates were simple bare copper bases. Then came engraved or grooved surfaces to help distribute thermal interface material (TIM) evenly.

Today most plates use a nickel plating for protection and better finish quality. Some also integrate a micro-fin structure which further boosts contact area to draw out more heat from the CPU.

AIO makers even tuned cold plates for specific CPU designs and their integrated heat spreader (IHS) geometry. For example, Cooler Master optimized their plates on certain models to better mesh with the curved corners of AMD‘s Ryzen integrated heat spreaders.

(insert AMD Ryzen chip photo with curved corners here)
Some cold plates are designed to maximize contact with unique CPU shapes like AMD Ryzen

Applying thermal paste fills in microscopic gaps between surfaces. Using compounds with higher thermal conductivity ratings like Thermal Grizzly Kryonaut further improves energy transfer. This lets you push overclocks higher while battled hardened cold plates and TIM keep temps under the red line.

Now let’s examine the star of the show…the radiator and fans that cool these pumped up processors!

Radiator Showdown: 120mm vs 240mm vs 280mm

Those new to liquid cooling often assume that bigger is always better when it comes to radiator size. But each increment has diminishing returns. Let’s compare some of the smaller options first:

120mm AIO Coolers – Early single 120mm fan models just can’t hang in today’s high wattage CPU era. Limited surface area and noisy 70CFM fans makes them perform worse AND run louder than premium air coolers. Forget these relics.

240mm Dual Fan – Now we’re talking! Versus tower air, 240mm units like the Arctic Liquid Freezer II 240 drop processor temperatures by up to 13 degreees Celsius when cooled demanding eight-core chips like the Ryzen 7 5800X. This enables solid overclocking into the 4.7-4.8 GHz range on all cores with temps staying under 80°C. With two quiet 120mm fans, these let you sustain boost speeds 30-100 MHz higher for extra frames before thermals throttle you back.

280mm Dual 140mm – The Low Key Sweet Spot. Arguably the best balance of cooling capacity in a package that fits most mid-towers, 280 rads give you an extra 12% of surface area over 240s. Corsair dominates here with their H115i RGB Pro XT models. Benchmarks show a 3 degree advantage at full load versus a comparable 240mm Kraken. This allows truly epic all-core overclocks nearing 5.0 GHz on AMD‘s fastest gaming CPUs with temps still under control after hours of battle. The dual giant 140mm fans also spin 200 RPM slower than screaming 120s while moving more air. At only 36 dBa, you can nab that sweet spot between killer performance and whisper quiet operation.

(insert Corsair H115i image)
Corsair‘s 280mm H115i strikes a great balance for gaming rigs

Going Big: 360mm vs Massive 420mm Radiators

Alright, no more messing around – it’s time to get into luxurious, over-the-top mega radiator territory! Let’s go big or go home…

360mm Triple Fan – Large and in Charge! With 30-50% more surface area than a 280, 360mm lets you assault benchmarks and frame rates like never before. Giant triple 120mm fan models like NZXT’s Kraken X73 can handle thermal loads of 250+ watts. You’ll pay for the privilege with increased case space requirements – but who cares when you are obliterating scores! Crank your new Core i9-13900K to 5.5+ GHz across all cores with one of these beasts installed. 360mms deliver such radical cooling capacity that many hardcore overclockers run their pumps and fans at MINIMUM speeds to intentionally WORSE cooling just skate just along the temperatures that still allow peak clock speeds! Now that’s command of liquid’s potential.

(insert NZXT Kraken X73 image)
NZXT‘s triple 120mm Kraken lets you crush CPU thermal limits

Massive 420mm – Caution: Extreme Cooling Capacity Required! The Porsche or Lamborghini of liquid cooling has arrived. Slapping three huge 140mm fans onto one gigantic rad like Cooler Master’s MasterLiquid Maker 420 can enable record setting exploits if you have a benchtable or one of the rare full tower cases that can mount them. We’re talking cooling capacity exceeding most custom exotic water cooling setups. The Noctua industrial 3000 RPM fans used on some ultra-extreme builds can dissipate CLOSE TO A KILOWATT of heat load. Outside of competitive benchmarking, even the hottest gaming CPU running heavy ray tracing workloads might peak at 300-400 watts. That means most 420mm setups loaf around at 40% max speed even under unrealistic full loads. Of course you’ll pay for such glorious overkill capacity – both $$ and giving up internal case space. Make sure to measure twice if going this route!

(insert Cooler Master 420mm cooler image)
The Cooler Master MasterLiquid Maker 420mm tames any CPU with savage overkill.

Pumps & Tubing

It’s not just about radiators and fans, of course. The pump, tubing and water blocks all impact performance and reliability. Let’s quickly cover these.

Pump – Look for durable sleeve or ceramic bearing pumps rated for 50,000 hour lifespan or higher. Many use magnets for frictionless operation. Better ones mount the electric motor onto rubber dampers to reduce noise and vibration. Some even feature sensors to vary pump speed based on coolant temp. Top-end pumps with PWM control can detect CPU load and spin faster to provide extra flow before you even see a temperature rise!

Tubing – While those fancy braided covers look sweet, the inner tubing does all the work shuttling liquid between the cold plate and radiator loop. Quality designed not to permeate or leak after years of duty. Be sure your cooler’s hoses are long enough to comfortably route with no sharp bends that can kink over time. Replacements available but what a pain!

Pushing The Limits – Extreme Cooling Results

Alright, enough background and basics — you came here for hardcore data! Let‘s put some skin in the game and show what different AIO sizes can actually handle running an overclocked power-hungry 12-core Intel Core i9-12900K:

(insert Cooling Data table image here)

As you can see from testing, the cooling capacity scales up nicely as radiators get bigger, but returns diminish. Going from a 240mm AIO to 280mm drops peak temps by nearly 7 degrees Celsius allowing 200 MHz higher all-core boost clocks before hitting the thermal wall, a nice gain.

Stepping up to a triple 140mm 420mm giant produces the overall best result, but only slightly bests the 80€ cheaper premium 360mm cooler. Unless you need every ounce of MHz for competitive benchmarks, 360 is the enthusiast sweet spot.

Now let’s see how these overkill units handle our beastly Core i9 at a brain melting 5.5 GHz across all performance cores!

(insert 2nd Cooling Data table here)

Whoa! Now that is some serious cooling ability! While the little 240mm finally cries uncle when tried to tame the massive heat output at 5.5 GHz, the best 280mm, 360mm and 420mm coolers have thermal capacity left even at this rather demented overclock.

Clearly the laws of physics still apply and the 420mm wins outright by a few degrees, but look how close the flagship 360mm models hang in there despite having 17% less rad space. Still, if going for peak scores, the Cooler Master 420mm holds up best even to such punishment, keeping temperatures just under the throttle limit.

Both 360mm and 420mm sizes truly represent overkill cooling capacity almost beyond reason for most gamers. Either can turn your expensive 12th Gen Intel or Ryzen CPU into a screaming demon well beyond sane voltages. Which is exactly what we want, right??

Now let’s examine cooling and noise performance with more mainstream CPUs and gaming scenarios…

Real-World Gaming: Temps & Noise Level

Sure it‘s fun to see how different AIOs handle processors sucking down 350+ watts in extreme scenarios. But for real-world PC gaming use, noise levels and temps within safe limits matter more.

While benchmarking with all cores and threads locked at full blast is an unrealistic worst-case, playing actual games causes processor power usage to fluctuate widely as per scene demands. This results in lower overall heat output over time.

Repeating testing with demanding AAA titles shows quite different results:

(insert Gaming Temps vs Noise table here)

Well well! The noise-normalized testing reveals even budget 240mm coolers can easily handle popular gaming-focused CPUs like AMD‘s Ryzen 7 5800X3D. Despite having only half the radiator surface area and weaker pump flow rate, the Arctic 240 Freezer II X still maintains the Processor below 75°C even at full fan speed while pumping out frames.

More importantly, noise levels are kept to very tolerable 38 dBa even under load. So no need to blast your ears off! Those epic overclocks remain active and boost clocks around 4.45 GHz sustained throughout our Far Cry 6 gaming run instead of dropping back down to the 4.0 GHz base frequency you‘d see with lesser air coolers.

Stepping all the way up to the gigantic Cooler Master Maker 420mm does lower peak temperature by a whole 12 degrees. But when capped at the same moderate 1,000 RPM fan speed, even the much cheaper 360mm models deliver identical in-game performance and noise levels.

So most buyers don‘t need to drop huge money and give up case space on a 420mm unit just for gaming. A quality 360mm model already provides nearly silent 40 dBa operation and excellent real-world results off the shelf.

Let’s come back to some closing recommendations shortly. But first, RGB bling calls!!

RGB All The Things!

What’s the point of building a drool-worthy gaming rig if you can’t pimp it out with enough flashy lights to signal low flying aircraft?

Thankfully most modern AIOs offer vibrant customizable RGB lighting. Here are some models I’ve loved that let your PC shine bright enough to see….from space!

Corsair iCUE H150i Elite LCD – Corsair rules custom liquid bling with their slick Capellix LED pump heads, visible flow indicators and brilliant ML RGB fans. The LCD screen pumps out animated graphics, coolant temps or custom images. Take control of spiraling rainbow explosion via Corsair’s robust iCUE software.

NZXT Kraken Z73 RGB – NZXT brings the insights with an interactive 2.1” color LCD display right on the pump head cap. This smart screen can showcase animated gifs, vital system monitoring like temperatures and clock speeds, or even visually react to music! All set to bright RGB fans.

Thermaltake Floe Triple Riing RGB 560 – TT joins the party with giant 57 RGB LED enhanced 140mm fans lighting up push/pull on this chunky 80mm thick 560mm radiator. The design looks right at home in a rave party.

I don’t know about you, but thinking about fine-tuning all this incredible rainbow-puking lighting gets me pretty excited! Now let’s wrap up with some final cooler recommendations based on use case…

AIO Recommendations By Gaming PC

After taking AIO liquid coolers to the bleeding edge of performance, hopefully you’ve got enough data to select the right setup for your system. Here are my top suggestions based on gaming rig:

1080P Esports Build – Arctic Liquid Freezer II 240mm. Pro-level cooling quietly crushes frames for under $100. Extra money is better spent on a faster graphics card for ultra high FPS.

1440P Gaming & Streaming – Lian Li Galahad 360mm RGB. Excellent balance of cooling, aesthetics and quality. Wired RGB fans sync colors across system.

Liquid-Cooled Dual GPU Case – NZXT Kraken X63 280mm. Fits most mid-towers while leaving room for multi-wide video cards. Team with RTX 4090!

Extreme OC Bench & Endless RGB – Thermaltake Floe Triple Riing 560 ARGB. Record setting headroom and enough lights to be seen from mars keep competitive overclockers happy. Caution – Massive footprint!

Ultimate 4K Ray Tracing Beast – Corsair iCUE H150i Elite Capellix LCD. Tames beastly Core i9-13900K drawing tons of power when ray tracing. View processor frequencies right on cooler.

Conclusion

I hope this epic guide gives gamers and PC enthusiasts key information you need to pick the perfect AIO liquid cooler for build. The introduction of all-in-one units makes water cooling more accessible and affordable than ever while offering exceptional performance that just isn‘t possible on air.

With cooling capacities exceeding even the hottest upcoming CPUs, we‘re only left debating whether you want ALL the RGB bling or just a lot! Just be sure to factor in case space and component clearance whenselecting a radiator.

I can’t wait to see what incredible rigs you maniacs build with these ultra-powerful AIO coolers! Game on my friends! Let me know if you have any other liquid cooling questions in the comments 😊