What's the point of no return with radiators? When is enough is enough?

[eBiz]

I was hoping to get a professional opinion with people with experience using watercooling. I was wondering what is the point of no return in terms of radiators? As in either how many radiators does it take to get to the point where adding more doesn't help exchange heat any faster.

 

Would a single 360mm radiator perform much worse than say three 560mm radiators?  Would the system with three 560mm radiators give higher stable clock speeds?

 

Thanks, any help is appreciated!

[ForsakenLive]

Once your fluid temps are near ambient temperature it's over. For a single CPU there shouldn't be a noticeable difference in going from a single 560mm to three 560mm radiators.

[Altecice]

^

As above you cant get your loop anylower than the current delta of the room its in (Ambient Temp). Adding anymore RADs will do nothing to lower it any further but you will still gain increased TDP cooling ability.

[Shaqo_Wyn]

I was hoping to get a professional opinion with people with experience using watercooling. I was wondering what is the point of no return in terms of radiators? As in either how many radiators does it take to get to the point where adding more doesn't help exchange heat any faster.

 

Would a single 360mm radiator perform much worse than say three 560mm radiators?  Would the system with three 560mm radiators give higher stable clock speeds?

 

Thanks, any help is appreciated!

 

The point of no return as you put it, is when you have enough rad space to dissipate the max TDP of the components you're trying to cool. This effectively means that your components will be at ambient temps under full load. Say you have an OC'ed 4790K and a OC'ed GTX 980 and together they have a max TDP 380W, there'd be no reason to go past 380W in heat dissipation.

 

You can push a CPU to the limit with a thick 360 rad. 3x 560's for a CPU would be just dumb..

 

Of course, having some extra rad space would facilitate running the fans at dead silent RPM's. 

[Whaler_99]

The other piece to this is your fans. A 560 rad with crap fans might actually under perform a  good 360 rad with top end fans. So, that is another consideration. Maybe throwing another rad at the loop isn't the best solution when some upgraded fans could also make a difference...

[airdeano]

adding more radiators (and quality fans) eventually will not pan-out to best

temperatures, but will prolong the system in duration of time before the the system

is fully saturated.

 

what might have taken 30mins to fully stabilize the temperatures with more radiators

will add more minutes to having the temperatures to finally stabilize.

 

going from a 360x 60 radiator to 2x 480x 60 radiators dropped overall device

temperatures 8°, but also took from 30 minutes to stabilize to 2.5hours to stabilize.

[Modzy]

Here is a simple example of one reason more rads can help to some degree. 



Lets say you run a CPU & single GPU. You could run them both on a single 360x30mm rad. But you may need to run the fans at higher RPM in order to maintain the lowest water temp. Adding a 2nd 360 for example would mean you could run all fans at their lowest RPM, and gain the same if not better overall loop temps.

Finding the balance can be tricky and comes how much noise you want from fans, what kind of temps you are aiming to have & how much money you have to through at it. Prior to my recent GPU upgrade. I was running my 2500K @ 5.2 & 2-way SLI 760s with a single 240x45mm rad + a 200mm rad. I built my entire case around being silent and also having the best airflow for the radiators. This meant sound dampening everywhere, sealing all passive air venting & positioning fans in an orientation so that the airflow in was matched by the air flow out.

I ran a single 120mm exhaust fan, at 1500rpm which was near silent but pulled a lot of unrestricted air. Then I had my 200mm rad in-taking through the front, and the 240 sucking down from the top. I ran all low rpm high static pressure fans on the rads sucking directly from outside the case. Not pulling any internal air. I tested this with my top 240mm rad, aiming to archive the same water temp of 24c, if I sucked air from inside the case I had the run the fans at 1200-1400rpm, while I only had to run them at 800-900 sucking fresh air. 




In short, if you are seriously planning a custom loop, and you care about audio levels or annoying fans sounds. You can make a huge impact simply by planning the right case with the right fans and radiators. My cpu/gpus ran between 19-22 idle and 38-44 under full load and highly overclocked. (5.2cpu/1350gpus). 

I have one rule about giving advice to anyone planning on building a water cooled system, you either want to do it for the fun and experience of doing it right. Which involves research/planning etc, Or you buy an AIO if you don't care, don't want to deal with loop maintenance or just want some of the benefits of h20 cooling. 




I generally explain it like this to anyone who wants to know. All this info is based on how much 120x30mm rad space plus static pressure optimized fans you need to effectively cool the average gamer/enthusiasts home PC. * Please note this can by altered when you can fit thicker or larger rads, eg 140/200mm rads).

CPU Only:
1x 120mm rad + 2x 1800-2200 rpm fans (push/pull) "starter & non-overclocker"
1x 360mm rad + 3x 800-1200 rpm fans (push) "basic quiet build mild OC'ing) -----  Adding a second set of fans in push/pull will help overall internal airflow better, but might only make a 3-5% difference to the loop temps.


CPU + 1 GPU:
2x 240mm rads + 4x 1500-1800 rpm fans (push) "basic duo, basic OC'ing on both" -----  Adding a second set of fans in push/pull will only create more noise for little-to-no gain.
2x 360mm rads + 6x 800-1200 rpm fans (push) "enthusiast duo, higher OC potential" -----  Adding a second set of fans in push/pull will help overall internal airflow better, but might only make a 3-5% difference to the loop temps.

CPU + 2-3 GPUs:
2x 480mm rads + 8x 800-1200 rpm fans (push) "pure enthusiast overclocker" -----  Adding a second set of fans in push/pull will help overall internal airflow better, but might only make a 3-5% difference to the loop temps.


An example of how thickness compares. if you have a single 480x30mm rad, you could swap this for a 360x45mm or 240x60/80mm and get near the same result, the only advantage of going longer rather than thicker, is you get more surface-to-air cooling potential on longer rads with more fans. But this is when a thing called maths and numbers start to melt my brain in explaining all the even more technical aspect of it. haha


Hope this helps anyone, I've been building h20 systems for about 10 years and these 5 configs seem to have helped a lot of my mates who got into it for the first time.

[Maxwit44]

I totally agree with @Modzy and @Shaqo_Wyn has said.

 

You must find the mean TDP of the system and build accordingly. But it can always go two ways. Decent rad's with ordinary fans, and vice versa. You'll always need to get the best of what you can afford. Fans and coolant always seem to be the most overlooked part, but yet are just as, if not more important than most other components.

 

Good example my system. My mean TDP is approx 350 watts of heat, yet the design power I aimed for is approx 450. With this being said, with average ambient temp in my study of 18 degrees C, My cpu and gpu average around the mid to high 40's with the fans at there lowest settings, under full load. If I had a K series cpu, this would give me plenty of overclocking head room for both my gpu and cpu, and see temp around the high 50's low 60's.