Should I Use An AIO For CPU Cooling?
First off, an AIO is short for “All In One”, which in this context refers to a liquid CPU cooler.
An AIO combines the parts necessary to liquid-cool your CPU into a pre-packaged solution that you bolt on in about 20 minutes.
The AIO combines the water block, radiator, tubes, fans, fittings, and pump into 1 sleek package.
Some popular models include the Corsair H100i v2 (afl), Fractal Design Celsius S24 (afl), Cooler Master MasterLiquid 120 (afl), NZXT Kraken X62 Rev 2 (afl), and the Thermaltake Floe Riing RGB 360 (afl).
A Quick Lesson On Water Cooling
The reservoir funnels cold water into the pump (generally directly below the reservoir). The reservoir helps during loop filling/draining, and thus while isn’t totally necessary, is extremely helpful.
Large reservoirs can hold more water, which means less goofing around with a funnel and distilled water.
The pump moves the cold water (and water overall) into the heat source (CPU), and out of the water block.
The CPU generates heat, which is conducted to the IHS (integrated heat spreader), or the shiny piece of metal with the CPU model written on it.
This heat is conducted to the water block which is laid on the IHS (there’s a thin layer of thermally conductive material between the IHS and water block, as the plate/plate contact isn’t perfect).
The water block uses an array of extremely thin fins to increase the surface area from which the heat can dissipate, and water is run through those micro-fins to move the hot water away from the heat source.
The hot water goes to the radiator via the soft/hard tubing, and is run through the radiator fin array to dissipate the heat out of the loop entirely.
The fans on the radiator move the hot air away from the loop itself, and out of the case.
The now-cold water moves from the radiator back into the reservoir, and the cycle repeats.
The AIO simply compresses this loop into a much smaller package, and removes the large maintenance issue that you get with a custom loop.
In the system above, the loop ran like this: Res->Pump->GPU->240 Radiator->CPU->360 Radiator->Res->Pump
The Risk of AIOs (and Water Cooling overall)
With water cooling, you are reliant on every part in the system working as it should, in order to have a functional cooling system. The blocks need to not clog, the radiators need to not leak, the fittings need to remain watertight, and the pump needs to remain powered.
If any one of these things fail, you generally have a big problem pretty quick (overheating).
This means the heat isn’t moved away from the source, and the cold water isn’t moved in to absorb the heat. You generally have an automatic thermal shutdown in a few seconds when that happens.
Not necessarily good for a production workstation.
If the radiator leaks, you’ll be losing coolant. While not an immediate issue on a big loop with a big reservoir, AIOs don’t have a reservoir, and thus a radiator leak is an issue.
If the fittings leak, you have a geyser. Water cools great...but only when it’s contained. Water and a powered up motherboard do not mix well.
Actually, water and electricity mix very well, but that’s not what you want. AIOs don’t have fittings, so to speak, but you get the point.
To The Good Part!
Reputable AIO manufacturers such as Corsair, NZXT, Fractal Design, and EVGA tend to put lengthy warranties on their products, as they are that confident in their systems.
I’ve been using a Corsair H100i for 4 years straight now, with zero issues whatsoever.
AIOs aren’t as big and bulky as their respective air brothers, and thus put less physical stress on the motherboard. All you have in the AIO is the pump head, soft tubes, and the radiator (and fans). No big monster metal air cooler!
We’re so confident in the modern AIO, that we have no issue recommending the use of an AIO in a desktop computer, and frequently design systems with AIOs used.
At this time of writing, we’re getting ready to build a gaming+media server computer that uses TWO AIOs, one for the CPU, and one for the GPU (removal of the stock GPU air cooler is required).