140mm vs 120mm Radiators

[Organized_Chaos]

Forgive me for how naive this may sound.
I'm going to be tackling my first water cooling build in the near future and am trying to make a judgement call on which radiator(s) to go with. I'm going to (for better or worse) attempt petg instead of soft tubing and since that will be challenging enough for my first water cooled build, I was hoping to only have 1 rad to worry about.

Popular opinion seems to suggest a 240mm rad for each overclocked main component. My question is - If I want to cool both the cpu (probably will be 8700k) and video card (likely a gtx1070), will going with a 420mm rad instead of 2 *240mm rads give effectively the same cooling?

By my potentially incorrect math, the two 240mm rads will have slighly less surface area than a 420mm rad.

Is this the correct way of looking at it?

 

[NatePo717]

Seeing as how 2 x 240mm rads give you 480mm of surface area, assuming same thickness and fin density as the 420mm, they should give you more potential heat dissipation area. Though I think in the grand scheme of it all the difference will be pretty negligible.

Personally, I would go for the 240mm rads. The fan selection for 120mm fans for radiators is much better and if I'm not mistaken, those are more important of a pick overall than the 60mm difference between the radiators. Case compatibility will be better over all too.

My second attempt at water cooling was all bent acrylic with 2 x 240mm which I did in a Caselabs Mercury S3. Since loop order doesn't matter it wasn't too difficult to do the bends and make it look clean.

 

[Organized_Chaos]

So when people refer to rad surface area, the length is the main factor? I was looking at it in terms of square millimeters, with 140x420 being greater than 120x480.

I have a Phanteks Enthoo Luxe for this build which seems to have plenty of rad options so I'm hopeful that compatibility won't be a huge issue. But it also comes with 4*140 fans which is one extra reason why the 140mm rad was appealing.

 

[NatePo717]

I don't know why but I completely forgot about the width... Apparently I can't think in multiple dimensions today. Either way it's still pretty negligible. A difference of like 34mm x 35mm.

140mm stock case fans are going to be optimized for higher air flow but at a lower static pressure. Depending on the FPI of the rad they'd either be fine (lower FPI) or be rather restricted (High FPI) where you'd want something more geared towards static pressure.

I don't think you can go wrong either way. 2 x 240mm or 1 x 420mm. It should be more than enough cooling for what you are aiming for. That case shouldn't have any problems with either option for sure.

As you already have fans, the 420mm option will be cheaper in fan cost, fittings, and amount of tubing you'd run.

I went with a 280mm AIO on my latest build and somewhat regret it as I couldn't reuse my 120mm GTs which I loved the sound and performance of.

 

[Organized_Chaos]

No worries, I just appreciate the input

 

[StefanR5R]

Radiator surface depends on length, width, thickness, and fins per inch of course.

A medium or thick 360 mm radiator should already be sufficient to cool a reasonably OC'd 6 core CPU and a GTX 1070, IMO. Of course the more radiator surface, the lower the required fan speed.

Granted, once you OC a device, power dissipation could go through the roof. But since we are talking a current Intel CPU here, the thermal interface between die and heat spreader will probably limit the overclock sooner than the radiator size.

Regarding the thread topic:

A while ago I preferred 140 mm fans over 120 mm fans, but looking back, that was with comparably low-powered air cooled PCs which required only very low fan speeds. But my more recent impression from higher powered PCs is that 120 mm fans are superior regarding the performance to noise ratio.

 

[aigomorla]

As stephan said, you cant just look at surface area, and have to look at overall dimensions.

Thickness + Fin density also have a big role in how efficient a radiator is and also dictates which fans can be paired with them for optimal heat dissipation.

It may sound like rocket science, but once u understand the basic its quite easy.

Now that being said, I feel most 120mm radiators will be superior then 140mm counterpart because of the selection in fans.
You will not find a Nocuta Industrial PPC 3k RPM fan on a 140mm flavor, nor will you find a 2800RPM Gentle Typhoon.

Fans are very important, having a limited selection will give you some handicaps.

Also i do not recommend you going rigid tubing as your first build.
Just dont.... even some vets have difficulty setting up rigid tubing builds, because one wrong torque here, and that section falls.
Once that section falls without any secure form of clamps.. and well... RIP.... you will be crying.

I would use tubing + good clamps and later when you get more comfortable with water, then move onto rigid tubing.

 

[Organized_Chaos]

Very good points about the fans. I'll have to get some good static pressure optimized 120s for the rad.

I'll have to try and tear myself away from the idea of a petg loop - I had just in the last week convinced myself to brave the challenge of measuring and bending the petg. Had gotten pretty excited about the possibilities so, no guarantee of success. However, if I were to do soft tubing, are compression fittings not preferable to barbs?

 

[dlerious]

Also i do not recommend you going rigid tubing as your first build.
Just dont.... even some vets have difficulty setting up rigid tubing builds, because one wrong torque here, and that section falls.
Once that section falls without any secure form of clamps.. and well... RIP.... you will be crying.

I would use tubing + good clamps and later when you get more comfortable with water, then move onto rigid tubing.

How about for second build? I'll be using either the Monsoon Chain Gun fittings or the Free Centers. I have 12x3 feet of PETG to practice with (probably grab a few feet of Acrylic as well just for the heck of it).

 

[aigomorla]

my honest advice is if your comfortable with handling leaks and spills, as in you have done them enough not to freak out when it happens, go ahead.

Also note, i and many other vets usually cheat the leak test process when not using rigid because well, using good clamps / compression really holds the fitting in place so leaks are usually just a result of negligence.

But in a rigid setup, i would definitely not cheat the leak process.
I would make sure i have a towel even under everything as the rigid tubing are basically pushed into it and then tighten.
All you have is 2 orings holding the seal. I have seen rigids leak many times because they were not properly pushed in.

So that being said, if you can handle leaks and not freak out, then sure go ahead.
But to someone just joining the hobby, a leak can be a hobby ender.

So its best to go the traditional way until he/she gets more comfortable with setting up a LCS system.

 

[EXCellR8]

once I plumbed with Primochill LRT I never had the urge to use rigid again. definitely doesn't look as neat, but it's just so stupid easy and with good clamps it just doesn't leak, ever. i got boxes of that stuff just stacked up in my shop now; it's relatively cheap for the ten feet that they give you I can't not recommend it. comes in a lot of colors too I think.

 

[XavierMace]

You will not find a Nocuta Industrial PPC 3k RPM fan on a 140mm flavor, nor will you find a 2800RPM Gentle Typhoon.

For the record: https://www.amazon.com/gp/product/B00KFCRF1A/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

I've been running them on my 280mm radiator for almost 3 years now.

 

[dlerious]

my honest advice is if your comfortable with handling leaks and spills, as in you have done them enough not to freak out when it happens, go ahead.

Also note, i and many other vets usually cheat the leak test process when not using rigid because well, using good clamps / compression really holds the fitting in place so leaks are usually just a result of negligence.

But in a rigid setup, i would definitely not cheat the leak process.
I would make sure i have a towel even under everything as the rigid tubing are basically pushed into it and then tighten.
All you have is 2 orings holding the seal. I have seen rigids leak many times because they were not properly pushed in.

So that being said, if you can handle leaks and not freak out, then sure go ahead.
But to someone just joining the hobby, a leak can be a hobby ender.

So its best to go the traditional way until he/she gets more comfortable with setting up a LCS system.

No problem with leaks. Paper towels are cheap, so no problem wrapping all the fittings (and everything else). I do the same with soft tubing. I guess I'll have to be a little more careful about accidental bumps - don't want to knock anything loose.

 

[aigomorla]

For the record: https://www.amazon.com/gp/product/B00KFCRF1A/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

I've been running them on my 280mm radiator for almost 3 years now.

oh wow when did they start making those?

 

[XavierMace]

oh wow when did they start making those?

Not sure, like I said, mine are almost 3 years old. They're a definite improvement over any of the fans I've found bundled with the Asetek AIO's, although NZXT's latest fans aren't bad.

 

[Billb2]

Using radiator length, width, thickness, and fin spacing to predict watts removed is a lot like using car color to predict gas mileage.

 

[bfun_x1]

If lower noise is important it'd be worth looking at eLoop B14-3 or B14-PS. I have the 120s and they're a noticable step above my Noctua fans in both noise and airflow. Their best in push on low to medium restriction radiators. People get mixed results with them in pull.

https://www.amazon.com/Noiseblocker-NB-eLoop-B14-PS-300-1200RPM-83-92CFM/dp/B0149M97NU

 

[XavierMace]

oh wow when did they start making those?

Also, just for reference, I get about 5c lower max temps on my current rig with the Noctua A14's on the radiator vs the AER P's included with my Kraken X62.

If lower noise is important it'd be worth looking at eLoop B14-3 or B14-PS. I have the 120s and they're a noticable step above my Noctua fans in both noise and airflow. Their best in push on low to medium restriction radiators. People get mixed results with them in pull.

https://www.amazon.com/Noiseblocker-NB-eLoop-B14-PS-300-1200RPM-83-92CFM/dp/B0149M97NU

I can't picture those being even average fans for radiators. Unless I'm reading their spec sheet wrong, they're half the airflow of the Noctua A14 iPPC 3k's and 1/10th the static pressure. They look to be about half the static pressure of the Aer P's as well.

 

[bfun_x1]

Static pressure may be low but they still performs well in the <= 1200 RPM range. It's a good choice for people that are considering quiet performance over temperature performance.

http://thermalbench.com/2016/02/12/blacknoise-nb-eloop-b14-ps-and-b14-3-140mm-fans/3/

 

[XavierMace]

If you're wanting to run your fans that low, you're probably better off skipping water cooling entirely.

 

[bfun_x1]

If I had to live with 3000 RPM fans I probably would skip water cooling. I choose water cooling for the great noise to performance ratio. That and it's a lot more fun than air.

 

[XavierMace]

You don't have to run 3000rpm fans at 3000rpm. But that gives you headroom if you need it. Plus, I'd love to see some actual number regarding your cooling capacity with that little airflow.