Fan adapters and radiators

Zarathustra[H]

Zarathustra[H]

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Hey all,

I am in the early planning stages of my first custom WC build.

From what I am reading, the consensus seems to be that for radiators, there simply aren't any good 140mm fans out there. The smaller 120mm fans are more or less always better due to higher static pressure.

Is this accurate?

So I guess, the follow up question would be, would there be any benefit from 140mm wide radiators, if 120mm fan adapters are used, in order to get good fans, or in that case, am I just better off going with 120mm wide radiators?

Much obliged,
Matt
 
I can't speak as to the quality of available fans, but I can speak a bit about radiators:

Surface area is everything in a radiator. The square size of the radiator isn't as important, as the fins run through the radiator and it's the fins that are your cooling surface area - a 120mm radiator that's 40mm deep will have more fin surface area than a 140mm radiator that's only 20mm deep. (I totally made up those numbers as an example)

So in that regard, 120mm vs 140mm -- doesn't really mean much. You need to consider the depth of those radiators as well. More airflow is better than less airflow, obviously. In that vein, there also isn't anything bad about using a 120mm fan with an adapter on a 140mm radiator. The radiator won't care, so long as air is going across all the fins.
 
It's a bit more complicated than that, but more or less correct.

A radiator with 100 fins (0.83fin/mm, 21fpi) at 120mm (long) by 40mm (deep) will have more surface area than another radiator with 117 fins (0.83fin/mm) at 140mm (long) by 20mm (deep):

100 * 120mm * 40mm * 2 = 960,000mm^2
117 * 140mm * 20mm * 2 = 655,200mm^2

But if the thicker radiator has a lower fin/mm count, then you quickly lose your advantage (80fin/120mm = 0.667fin/mm, 17fpi):

80 * 120mm * 40mm * 2 = 768,000mm^2

Yes, I know radiators use fpi, not mm--I only used mm for simplicity, since radiators' size is measured in mm. This also assumes the radiator uses the whole width for fins, which in reality doesn't happen, but that's fine for this comparison IMHO.
 
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140mm fans will move the same amount of air at a slower rpm resulting in less noise if that's important to you!
 
Brian_B said:
I can't speak as to the quality of available fans, but I can speak a bit about radiators:

Surface area is everything in a radiator. The square size of the radiator isn't as important, as the fins run through the radiator and it's the fins that are your cooling surface area - a 120mm radiator that's 40mm deep will have more fin surface area than a 140mm radiator that's only 20mm deep. (I totally made up those numbers as an example)

So in that regard, 120mm vs 140mm -- doesn't really mean much. You need to consider the depth of those radiators as well. More airflow is better than less airflow, obviously. In that vein, there also isn't anything bad about using a 120mm fan with an adapter on a 140mm radiator. The radiator won't care, so long as air is going across all the fins.
Click to expand...

It doesn't exactly work like that as thickness contributes to air restriction. Everything else being equal, thicker radiators have less airflow out of the same fans compared to thinner radiators. Whether that tradeoff is worth it depends on the speed of the fans being run. In Martin's testing, at 600 RPM, the Alphacool ST30 outperformed the UT60, both of which are very similar in construction. At higher RPMs, the UT60 pulled ahead.

Also, if you have both 120 and 140mm mounting points in your case, you can get radiators of the same thickness. It's not like 60mm thick 140mm radiators don't exist. And when you get to multiple fan radiators, that extra 20mm adds up. A 3x140mm radiator has 58800 mm^2 of surface area, a 4x120mm radiator has 57600 mm^2 of surface area. A 3x140 has more surface area than a 4x120.

As for quality 140 fans, the selection available has greatly increased in the past 2-3 years. Noctua has 120 and 140mm variants of almost their entire fan lineup, if I recall correctly. Other companies as well have both 120mm and 140mm versions of their high performance fans. Though the king of watercooling fans, the Gentle Typhoons, probably won't have a 140mm variant anytime soon.
 
Tsumi said:
As for quality 140 fans, the selection available has greatly increased in the past 2-3 years. Noctua has 120 and 140mm variants of almost their entire fan lineup, if I recall correctly. Other companies as well have both 120mm and 140mm versions of their high performance fans. Though the king of watercooling fans, the Gentle Typhoons, probably won't have a 140mm variant anytime soon.
Click to expand...

Yeah, I have been looking around. Corsair finally launched 140mm SP's, but they all have LED's (ugh) and besides, I've found their fans to be noisy for the amount of air they push anyway.

I have been reading good things about the 140mm Noctua Industrial 3000rpm PWM fans. A bit noisy at full bore, but that's what PWM is for. $30 per fan seems a littleuch though.

What good static pressure 140mm fans have you come across?
 
Nobu said:
It's a bit more complicated than that, but more or less correct.

A radiator with 100 fins (0.83fin/mm, 21fpi) at 120mm (long) by 40mm (deep) will have more surface area than another radiator with 117 fins (0.83fin/mm) at 140mm (long) by 20mm (deep):

100 * 120mm * 40mm * 2 = 960,000mm^2
117 * 140mm * 20mm * 2 = 655,200mm^2
Click to expand...

*cough* you missed a dimension. Radiators have Height, Depth, *and* Width. ;)

That being said, depth shouldn't really be considered when comparing 120mm to 140mm radiators. They are both available in many different depths so it isn't a deciding factor in which one to buy. Also as Tsumi correctly points out, thicker is not universally better, and raw surface area is not universally better as your calculations are trying to show. Airflow is very important, and as you increase depth, and increase fin density the airflow goes down. The trick is to find the perfect balance of the two.
 
I've always been interested in the B-gears B-blaster 140mm fans. It utilizes a double ball-bearing hub, similar to the Gentle Tyhpoons, but the blades are different. The other ones are the Aerocool DS fans and Cougar.
 
Regardless of width (and I said I was assuming the full width: 120mm or 140mm wide, so 100 or 80 fins divided by 120 or 140), the more fins you have the more surface area you'll have, but you'll also have more restriction (given the same width).

I wasn't saying depth is more important, or surface area for that matter. I was showing how his analsys was incomplete, as there are more factors to consider (the number of fins being one, and airflow being another). You might also mention that the design of the fins, and how the water (and air) is routed through them, is also important for cooling. However, he was "correct" in that surface area is important. If you are unable to transfer the heat from the liquid to the fins (fins are saturated with heat), then it doesn't matter how much air you have going through, you'll be limited in how much you can cool your liquid. Similarly, if you don't have enough airflow, then it doesn't matter how much surface area you have, because the air will saturate with heat before it exits the radiator, and then you won't be able to dump any more (It'll be stuck in your loop).
 
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His analysis wasn't just incomplete, it was wrong and misleading. And your analysis was incomplete and misleading as well.
 
I'd like to know how mine was misleading, but I'm not going to argue about it, especially because I don't know. I do know it was incomplete, but my intent was not to mislead.

Edit: By the way, in case you missed it, I accounted for the width of the 140mm rad in my calculations. The reason I increased the number of fins was to keep the fpi count the same, so that the comparison would be meaningful. I had hoped, however, that you would be able to realize on your own that a larger radiator with the same number of fins (lower fpi, thus more room for air) and more surface area (so a greater cooling capacity) would perform better. Maybe I was being too optimistic? I'll amend my post here, so that it's explicit:
A radiator with 100 fins (0.83fin/mm, 21fpi) at 120mm (long) by 40mm (deep) will have more surface area than another radiator with 117 fins (0.83fin/mm) at 140mm (long) by 20mm (deep):
100 * 120mm * 40mm * 2 = 960,000mm^2
117 * 140mm * 20mm * 2 = 655,200mm^2

But if the thicker radiator has a lower fin/mm count, then you quickly lose your advantage (80fin/120mm = 0.667fin/mm, 17fpi):
80 * 120mm * 40mm * 2 = 768,000mm^2

However, a larger radiator with the same number of fins at the same thickness will have more room for air to flow and more surface area, so will perform better with lower static pressure fans or with identical fans at a lower speed.
100 * 120mm * 20mm * 2 = 480,000mm^2 @ 0.83fin/mm
100 * 140mm * 20mm * 2 = 560,000mm^2 @ 0.71fin/mm
Click to expand...
Better?
 
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You still aren't accounting for the width, all you did was make them twice as long. Hint, the area of a square with 10 inch sides is not 20 inches, it is 100 inches.

That being said, it is a mostly pointless exercise. There is no way to take the raw surface area vs fin area vs depth vs restriction and come up with a decision on which is the better radiator. We just don't have the right information. It is best to simply look at reviews and make a decision based upon what your case can support and what your goals are with your watercooling system. Make your decision based upon basic rules of thumb and reviews.

1) A larger radiator is generally better.
2) A thinner radiator or low fpi is good for slow fans.
3) A thicker radiator or high fpi is good for fast fans.

Ultimately though the biggest influence in your radiator performance is going to be the size of it. Even the best 120mm radiator isn't going to perform as well as a midling 2x120mm radiator. It is just really hard to make up for the size difference.

So OP, I would say go for a 140mm radiator. There are quite a few fans for 140mm now because they have grown in popularity in the past 3-4 years.
 
It's all about size, eh?

I wonder if I could strap one of these to a modded side panel door and have fans blowing out through it from the inside :p

35501.jpg


9 140mm fan spots :p
 
I didn't make anything twice as long. the x2 multiplication is because each fin has two sides (we aren't talking about a square here, it's a rectangular prism). The first number is the number of fins. If you want the same fpi, you need to increase that number as the width of the radiator increases. That's where I account for the width. We know the width of the radiator (either 120, or 140, or whatever), so given a certain number of fins or a certain fpi, we can figure out the other number.

Edit: Op: I mean, you could. I've considered it...but I don't have the money or motivation to do that myself. lol
Besides, unless you're cranking out some serious heat, it's overkill. Once you reach ambient temps, you've hit a wall.
 
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only one thing to know about big radiators.......MoRa.......that is all.:D
 
magoo said:
only one thing to know about big radiators.......MoRa.......that is all.:D
Click to expand...

According to every comparison I have been able to find, the Phobya 1260 with 9 fans beats the MoRa 3 Pro with 9 fans quite handily.

The Mora 3 Pro - however - usually winds up on top when tested with 18 140mm fans in push-pull, simply because no one seems to test the Phobya 1260 with 18 fans for some reason, only with 9.
 
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