Alphacool radiator much thinner than advertised

[ASNielsen]

I just received a new 280mm Alphacool NexXoS ST30 V.2. And boy was i disappointed.

It's supposed to be 30mm thick. The mount is indeed 30mm. But the actual radiator part of the radiator is only 20mm thick. There's a 5mm deep gap on each side of the mount, see photo attached. It's not a 30mm radiator, it's a 20mm radiator in a 30mm casing.

Also bought the ST25, exact same issue. It was supposed to be 25mm thick, but in reality it's more like 15mm thick.

I currently use a corsair AIO system, their 30mm radiator is a full 30mm thick...

Why are the Alphacool radiators so thin? There can't possibly be any performance reasons behind it can there?

 

[Eddy]

That is quite normal. You need space for two things. One is for the mounting screws of the fans and more importantly, you need space for the air of the fans. If the fans were to rest exactly on the cooling fins, the cooling capacity would be significantly lower. Only with an air cushion between the fan and the cooling fins can an even air pressure build up that ensures optimal cooling.
Time me a radiator that is not like that. Look here, this is a Corsair radiator or a Black Ice Nemesis.... is basically the same as Corsair does not have its own production for radiators.

https://cwsmgmt.corsair.com/pdp/hydro-x/radiator/xr5/xr5_threads.png

 

[ASNielsen]

Hi Eddy thank you for your response!

Looking around it seems many radiators do indeed have a few millimeters gaps.

However, my Corsair radiator that i am comparing with is this one: 115 XT Pro. It has almost no air gap. The radiator inside their 30mm casing is 28mm thick. Not just 20mm like the Alphacool V.2 ST30.

The 115 XT Pro is a new new premium model though. Looking at the older/cheaper Corsair models, they appear indeed to also have fairly large gaps like the Alphacool radiators.

I do not understand your argument that having such a large gap between the radiator and the fan increase performance. Even if this is true, then why do you have the big gap on both sides of your radiators? One side should be enough..

To me, looking at the products i bought, it seems like the reason for having large gaps is that it makes the mounting/casing design simper and hence cheaper to produce.

Is Alphacool planning on creating radiators without such large gaps? For a 30mm radiator, a whole 10mm of air seems wasteful.

I'm not trying to talk down Alphacool products. I also bought many other component, like fittings, pumps, CPU/GPU blocks, they all definitely have a premium feel to them!

It's only the radiators that disappointed me seeing how the Corsair 30mm radiator i already had is whopping 40% thicker than the Alphacool NexXos V.2 ST30 (28mm vs 20mm).

 

[Luckystricker]

Hi @ASNielsen


I can't explain that to you exactly about the gaps on both sides of the radiator.

For mounting in, on or outside of the housing. Many manufacturers have their name / logo on the side. But what do you do now if you want the radiator instead of the top on the floor.
Then it depends on you want to install the fans in push or pull or push / pull.
With some fans, the rotor looks slightly out of the frame (bearing play), i.e. when pulling the rotor would then drag against the cooling fins.
On the other hand, the distance between the cooling fins and the fan is noticeable in the cooling performance.
Because the air can be better distributed over the entire surface and can also get behind the engine and flow through the radiator.
A good example are shrouds (I use 7mm thick myself, that made a difference of 4 ° C for me at a speed of 600rpm), so the fan comes further away and is sealed at the corners.

The pure radiator strength says little about the cooling performance itself, that depends much more on the fans.
In addition, the Alphacool radiators are made of copper, while those of the Corsair are made of aluminum (copper is a better metal for heat transfer than aluminum).

This is my level of understanding how and why in this regard now.
But I also think that one could write a novel about this topic here.

Best Regards

 

[ASNielsen]

Hi @Luckystricker

Yea that's true, having wide air-gaps on both side does indeed give complete flexibility to never have the logo upside down, even in strange case designs and push-pull combinations with fan heads that protrude out.

But personally I'd love to have the option to buy a radiator with the air-gap only on one side, given that the gaps are so big ?

For thick radiators the difference is negligible. But for the slim ST30, having the gap only on one side would mean 24mm of heat-fin surface instead of 20mm. That's 20% extra cooling surface without taking up more space in the case! For the ST25, it would give 25% extra cooling surface without taking up more space.

 

[Luckystricker]

Hi @ASNielsen

I can understand you as you mean it.
Personally, I now have no idea about product planning, manufacturing and sales.
I just think that the effort would be too high and interest too little. Of course it would have advantages, but then in principle they would have to bring out two new types each of the ST30 and ST25. Where one has the air on one side and the other on the other.
I think that, in turn, would confuse a lot of people which they then exactly need.

This is now my own train of thought. I hope my English isn't too bad. ?

 

[ASNielsen]

Yea, i guess it's quite niche, and looking around it seems there's already a few radiators out there with smaller gaps for people who want it.

Thanks for answering though. If i had more experience with water-cooling i suppose i would have known already whilst planning my build ?

I've decided to just get a larger case instead of trying to cram everything down my current medium sized case. Bought the Fractal Design 7 XL, it looks big enough to fit two 420mm Alphacool XT45 radiators