Re: In days of yore
Quote: In tests water cooling is not "better" as such.
Granted 'better' is subjective, but a good water cooler will always * beat a good air cooler. Water is just more efficient at moving heat around, and normally you'd mount the water cooler rad on the top of a case, venting heat directly outwards, unlike an aircooler that vent's within the case and so then needs that heat removing via case fans. (You still have case fans in a water cooled system, they just have to do less work as they are only moving GPU and motherboard heat, so tend to run slower, so quieter).
* 'beat' is only by something like 2-4 deg c. Which may not matter to you, and so may not be worthwhile depending on your use case, but could matter to someone else.
* Also a good aircooler will beat a bad, or mediocre water cooler.
Gamers Nexus did a good video on this only a few months ago. Liquid Cooling vs. Air Cooling Benchmark In-Depth
That includes running the coolers at 100% fan speed (so best cooling performance irrespective of noise), and also noise normalised testing (so same db for all coolers).
Quote: Is it more flexible in positioning in cases?
Yes, although that's kind of obvious ;-) An aircooler can only go in one location, whereas a water cooler rad can be (depending on case) mounted on the top, front or bottom of the case. Most modern mid tower cases are designed with water cooling in mind.
Personally, I'd also say overall, an All-In-One is easier to fit, at least compared to a good, i.e. large tower, air-cooler. (Based on experience with both types). Although a simple small aircooler (like the sort AMD provide with their CPU's) is easier still.
Quote: Does it allow for larger radiators?
Yes, the standard sizes (for an All-In-One) are normally 120, 240 or 360, which have 1, 2 or 3 x 120 mm fans respectively, or 140, 280, 420, which have 1, 2 or 3 x 140 mm fans respectively. With the radiators matching the area that the fans cover. So a 280 would have a rad double the size of a 140 etc.
Radiators are usually slightly wider than the width of the fans, and are longer than the posted size.
For example a '280' (one of the more common ones in use), uses 2 x 140mm fans, so the rad would be around 143mm wide, 315mm long (as it needs to accommodate the fans + a small reservoirs at one end, plus the pipe connections at the other end), and around 30mm thick. Although these sizes vary by model and make.
Quote: Yes. Is it "better"? Results may vary. ;)c
Indeed they do vary :-)
Edit. And just to mention, all the above is related to AIO (All-In-One) rather than a custom loop.