Air cooling vs Closed loop liquid cooling
Both these types of cooling are really air cooling, as in a closed loop water cooler, you are blowing or sucking air through the radiator via a single or two or three fans. But for the sake of argument, let's call a heat sink and a fan air cooling, and closed loop water cooling water cooling.
My current CPU cooling solution is a Be-Quiet Dark Rock Pro 2, a high end air cooler. Cooling performance is excellent, and as the name suggests, it runs very quietly.
One problem with the Dark Rock Pro 2 is its very large, and covers the RAM slots. So replacing or adding RAM is impossible without first removing the CPU cooler.
I thought I would give a closed loop water cooler a try. My case (Antec P280) can only accommodate a 240mm radiator at the top of the case.
I decided on the Corsair H100i V2.
Fitting was easy, and now my RAM slots were clear. But that is where the good news ended.
My system, a SkyLake i7 6700K is overclocked to 4.6Ghz for 24/7 use.
At full load these are the comparable results.
Be-Quiet Dark Rock Pro 2 = Core temp average of 72c.
Corsair H100i V2 = Core temp average 69c
So the Corsair managed to lower the temps by 3c.
Be-Quiet Dark Rock Pro 2 = Core temp average of 22c.
Corsair H100i V2 = Core temp average 23c
This time the air cooling won.
Now for the bad news.
The noise from the Corsair H100i V2 when running at max during the full load test was unbearable to my ears, whilst the Dark Rock Pro2 at max was barely noticeable.
At idle the Dark Rock Pro2 fans are spinning at only 450rpm, and inaudible in my very quiet PC case.
The Corsair at idle was fairly quiet, but I could hear the water pump.
Not only that, but the motherboards VRM's when using the Corsair H100i V2 were running very hot. That isn't surprising as the only air cooling the VRM's when using a closed loop cooler is the air being sucked through the VRM's via the rear case exhausted fan which is really to far away from the VRM's to be effective.
The Dark Rock Pro2 in contrast expels the air from the cooler, through the VRM's, so the VRM's on the motherboard are being actively cooled via the Dark Rock Pro2.
The Corsair H100i V2 was returned for a refund, and I'm now once again enjoying a quiet and well cooled CPU.
The moral of this story is.
Whilst a closed loop water cooler may give slightly better performance when compared to a high end air cooling solution, and give unrestricted access to your RAM. They make much more noise, and at least in the case of the Corsair H100i V2 and I'd expect most similar products. They won't cool your VRM's.
Another thing I noticed.
The build quality of the Dark Rock Pro 2 is light years ahead of the Corsair.