Question H150i cooling 9900k

lordreyrey

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Feb 3, 2012
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Evening everyone.

Ok. My recent build has an i9 9900k being cooled by a corsair h150i aio. The case is a corsair crystal 570x.

The current setup has 3 LL120 fans pushing air through the front mounted radiator as intake.

3 other fan's, hd120 fans, are mounted as exhaust. Two in top and one in back.

My question is this....

Will i benefit from adding 3 more ll120 fans to my radiator and a push pull config?

And if I do benefit from that, then doesnt ehat affect my case air pressure, since 3 and 3 are equalized now?

Thanks everyone.
 
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Darkbreeze

Titan
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It has no effect on case pressure really, maybe VERY minimally, as you are still only adding as much air to the case as the front three fans can manage to flow through the radiator. The rear three fans on the radiator in the pull configuration are MAINLY going to be assisting the front fans, to make their life easier by reducing the work required to overcome the static pressure resistance of the fin structure. They will also help to eliminate any dead spots or reversion leaks that a push only configuration may have.

When you have fans on the back of a radiator or heatsink pulling in addition to fans on the front pushing, you eliminate any little pockets where airflow tends to not happen because instead of the front fans only effecting a push against the static and pressure resistance, you are now sucking air and creating a negative pressure situation that makes it much easier for the front fans to push.

You are not going to see some amazing increase in performance for adding three pull fans, maybe 3-4°C overall. Also, your overall internal pressure shouldn't change much if any either. There might be a negligible change towards positive, but it's more likely that it will remain about the same.
 

lordreyrey

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Feb 3, 2012
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Ok.
I'm also getting a commander pro.
How should I set this up?

Currently the 3 ll120 fans on the radiator are connected to the h150i pump to power and to a hub for rgb. And the other 3 hd120 fans on the case are connected to a hub for rgb and directly to the mobo for power.

Do I just connect the 3 new ll120 fans to the commander pro, and leave the other 3 ll120 fans connected to the pump?

That would mean the pump is only connected to 3 of the 6 fans on the radiator. Does that matter?
 

lordreyrey

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Feb 3, 2012
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What about using the same fans?
I could move the hd120 to the back of the radiator and use the 3 new ll120 on the top of the case as they look nicer.

That would leave 3 ll120 on front of radio and 3 hd120 on back.

Internet seems divided on if that's ok or not...
 

Darkbreeze

Titan
Moderator
Honestly, those LL120 fans have fairly low static pressure to be used on the front of a radiator and they have too low of CFM to use on the back if you were to use the HD120's on the front, because they'd become a restriction for the higher CFM and higher static pressure HD120's.

Using the LL120's on the top or back is fine, good even, but I think I'd use the HD120's on the front of the radiator and then if you want to use some pull fans either get three more HD120's at some point OR get three even higher CFM fans to mount on the back of the radiator in the pull position.

Exhaust fans don't need to be high static pressure, but having a high CFM is desirable when possible, but those LL120's will work fine as rear or top exhausts.

Putting them behind the HD 120's on that radiator would be much like blocking the airflow out the back of the radiator with a sheet of cardboard that had holes punched in it. Yes, some air is going to get through, but it's going to be restricted since they move less air than the front fans.
 
Use the Commander Pro to power all 6 front fans. It'll work the same as using the pump, using the iCue software. The motherboard doesn't power the fans, that comes from the Sata power, the only reason for the motherboard cpu fan header is the pump rpm, fan rpm is from the usb. So the fans control is just as easy from the Commander instead.

I'd put the 3x original HD's on the back of the rad. The LL's are not that good for rad fans, but look good. So I'd leave them in place, the HD's will help out more than hinder any performance there, more like as if the LLs didn't exist and the 3x HDs were used in a pull config.
 

Darkbreeze

Titan
Moderator
Seems a waste to put fans with 2.5mm H20 static pressure, on the BACK of a radiator or heatsink, unless you have another set with similar static pressure on the front.

Much the same as you probably wouldn't put high static pressure fans in exhaust locations unless it was due to other qualities of the fan.
 
I agree. But he already has those fans as exhausts, and likes the looks of the LLs so wants get 3 new fans for the exhaust position. I just suggested repurposing what he already had since new LLs on the back side of the rad made even less sense.

But then again, that intake air shouldn't have any issues getting under the gpu as strong as those hd's will move the air.
 

Darkbreeze

Titan
Moderator
I think the better option is using those HD's, whether on the front or back of the radiator, by themselves. Whether you put the lower CFM fans in front of or behind those HDs, they become a restriction as the HDs have about 20CFM higher airflow per fan than the LL's do.

But if you're going to use both no matter what, then I'd agree that your premise of using the HDs on the back of the radiator and the LL's on the front is the lesser of two evils and will at least result in a pleasing aesthetic.
 
Well if you'd like to be nice, do the full gammut of tests.
Run Prime95 26.6 small fft for half an hour per test (let's coolant get to equilibrium under 100% constant load)
Do just LLs on front, just HDs on back, then both, both ways. If you can read liquid temps as well (think you can in iCue) that'd be great.

That'd give real world results, not only for DB and I, but also any subsequent readers interested in the LL fans and whether they'll hold up against a higher performing sp fan vs push/pull setup.
 

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