Originally Posted by prava
Nope. Its not something that simple. Different pwm designs will behave differently based on the pwm signal they are feeded. The simplest example you have it on the H220 itself:
You can clearly see that Swiftech intended the pump to be variable while you keep your fans at 100%, so that you make your pump a bit more silent whilst not reducing performance from lowering your fans rpm's. Kinda wise decision.
You can't simply compare apples to oranges. For starters, the H220 is superior to the RS240.... so, improving the rad would be as easy as understanding how rads affect performance. At the end of the day rad increase decreases the Delta T more or less linearly... which means that improving rad capacity by 50% will lower your Delta T by 33%.
So, how this Delta decrease will affect cpu temperature? Each block has a certain Delta T water/core (how higher the core temperature will be over the water temperature) that varies depending on the cpu used, voltage, load, frequency, IHS, and some other variables... you add such water/core + your ambient temp + the water/air Delta T of your system and will have the improvements.
Let me put an example. Lets imagine the following:
- 200W cpu
- 35ºC water/core Delta for that particular cpu and setting (its a very average number, better blocks might get better temperatures)
- 25ºC Ambient temperature
- 1550 rpm yate loons
- C/W = 0,031 (like a Swiftech MCR220, as tested by Martin)
a) Swiftech MCR220: the cpu temperature would be: 0,031*200 + 25 + 35 = 66.2ºC
b) Swiftech MCR320: the cpu temperature would be: 0,021*200 + 25 + 35 = 64.2ºC
Keep in mind one thing: the lower you keep your fans, the bigger the difference will be. If we were to run our fans silently.... les say, at 1000rpm, the differences would be:
a) Double rad: 70ºC
c) Triple rad: 66.6ºC
An so on.
So... yes, performance difference wouldn't be too big at all, but the bigger the rad the more silent you can keep your fans. So, unless you want the really best or you plan to put a very heavy load on your system, I wouldn't bother with a triple rad at all. Even more: you could put a gpu into the H220 provided you wouldn't expect to run both the cpu and gpu at 100% load at the same time.
People underestimate many things about watercooling...