ChipFlip
A used AIO liquid cooler tracks at $89. A used air cooler with a real reputation tracks at $69.99. A budget air cooler goes for $24.99. Before spending more on liquid cooling, here's what that $65 gap between the cheapest and most expensive option actually buys.
The AIO's real advantage isn't always what buyers assume
A 360mm AIO like the one tracked here moves heat away from the CPU more effectively than most air coolers, particularly under sustained heavy load. That matters for high-power chips pushed to their limits. It matters much less for a mid-range CPU running typical workloads, where a good air cooler keeps up just fine.
Air cooling still wins on reliability
An air cooler has no pump, no tubing, and nothing to leak. That's not a small thing. A failed AIO pump can mean a dead CPU in the worst case, while a failed air cooler just means the fan stopped spinning, which is easy to diagnose and cheap to replace. Used cooling hardware carries more of this risk than new, since you don't know how the previous owner ran it.
What the $70 buys over the $25 option
The be quiet! Dark Rock Pro 3 at $69.99 sits well above the Deepcool AG400 at $24.99 in both cooling capacity and, generally, noise levels under load. For a mid-range or higher CPU pushed reasonably hard, that gap is worth paying. For a lower-power chip doing basic tasks, the cheaper cooler is often already more than enough.
Buying either used
Check for any visible corrosion or residue around an AIO's pump housing and tubing before buying. On air coolers, spin the fan by hand and listen for grinding or excessive play in the bearing. Neither issue is always visible in listing photos, so ask the seller directly if anything looks uncertain.
Bottom line
Don't default to AIO liquid cooling just because it looks more premium. Match the cooler to the actual chip and workload, and remember that a $25 air cooler handles plenty of real-world builds without any compromise that matters.