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1.5 cm fans vs long aio screws


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Hey this is just a better be than sorry kind of question.


Im having difficulties fitting my H150i pro on the top section of my case (o-11 XL) due to using push pull.


It was a very tight squeeze last time I did it.


So I was thinking of switching the stock fans I got out with Noctua NF-A12x15


So my question is. If I use those normal long screws for 2.5 cm fans would there be a risk of me ruining my aio?

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You can't use the ~28-30mm screws on the 15mm fan. That will put you 10cm into the radiator. You would need to source some 6-32 machine screws approximately 17-19mm in length. However before doing that, I would consider the points below.


15mm fans do not work very well on a radiator. This is an area where fan thickness matters and you are not gaining much in terms of the pressure generated. That pressure is additive between the fans, while airflow is not. In fact, it is possible the 15mm become resistance for the other set.


Given that, it's hard to say adding the extra set of 15mm fans is worthwhile in any circumstance. Probably even more so for a Ryzen 3000 series. You will be limited by CPU temperature and voltage, but not by wattage or the radiators ability to dissipate that wattage. Even the 3900X with 12 cores is not going to create a large coolant rise from CPU wattage. There just isn't that much to get rid on these 7nm models. It is more likely most of your coolant temp level will come from that location at the top of the case.


To that end, if you are running an air cooled GPU in an O11D/XL, you may want the H150i in the side slot as intake. Bottom/side in, top/rear out is about only way that makes much sense. This is especially true with that side position where the fans get choked off when set as exhaust because of their position in relation to the small side glass. Putting the H150i in the side would also allow you to run push-pull with conventional 25mm fans and a 30mm thickness or less radiator, if you are determined to do so.

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Hello, thank you so much for the reply.


The 150 mm fans are most likely gonna be at the exhaust while I will have corsair QL 120 as push.


I have atm a MSI gaming X 1080ti but Im thinking of switching it out with 3090 EVGA kingpin if I could get my hands on one and put it on the side.


The reason I have the AIO on top is both because the CPU tempo wont fight against the GPU that much especielly when I should eventually upgrade..


I had a ryzen 3900x but it sadly died few months ago so Im atm waiting for the next gen of that aswell.


Im defintly gonna try look for a new set of screws.


Thank you very much for all the info Im defintly gonna reconsider these short fans and see if I have other options

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OK then, so theoretical planning...


The problem with the 3090 Kingpin in the side (I am assuming it's a hybid AIO GPU) is the small side glass really chokes the airflow to those fans when used as exhaust. If you use it as intake and it can pull through the back, it breathes much better. However, that will be at expense of putting some much warmer air into the case. You can expect about a +12-13C coolant rise if that is 280mm radiator and a little more if 240mm. That likely means exhaust air temp from the GPU rad of between 35-45C depending on your base. Your top CPU radiator then gets to inhale that air. Essentially, you pass on the temperature penalty to your CPU cooler. If it has to be done this way for whatever reason, use the GPU AIO as side exhaust, take the warmer GPU temps, and pull the small side glass if things get too bad. That will allow the side exhaust to breathe free again.


Ideally, you'd like the GPU radiator up top exhausting and the CPU radiator on the side as intake. No matter what you get for a CPU next, at most you will see a 150W average load during mixed used like gaming. That is an easy load to handle with a small coolant rise. That means it's exhaust will not affect the much warmer GPU coolant temp above. Essentially you are putting the hottest stuff up top to minimize any add on effect from other components.


Make sure you try the H150i with a single set of fans first to get a baseline for comparison. I'm afraid the extra 15mm fan layer may not help much at all.

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Hmm yeah that does sound smart. Im atm using bottom and side as intake and top and back as exhausts.


The kingpin will also have a 360 radiator this time around. But if I can to the top of the case and be used as exhaust and if it indeed does benefit the overall temps then I would defintly go for that



Thank so much again for the info I really appreciate it :biggrin:

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