Fan placement advice

[Gothfather]

I have a Phanteks Enthoo pro case with two bottom 120mm intake fans and two 140mm front intake fans. For exhaust i have 3 140mm fans 2 on the top of the case one at the rear. This creates and intake of 221.8 CMF and an exhaust of 181.2 CMF. I am adding an EVGA GTX 1080 FTW hybrid video card which has a small radiator and a 120mm fan. I am pretty sure adding this 4th exhaust fan will push my case from a positive pressure case to a negative or neutral pressure case. I prefer to keep the case at positive pressure because it is in a room that gets dusty.

 

I have room for 3 top fans, 2 front fans, two bottom 120mm fans and 1 rear fan. So this radiator fan from the video card is going to fill up all my fan slots so adding a fan isn't an option.

 

So should i move the rear exhaust fan and put it in the open top fan slot and switch it to intake and add the video card radiator & fan to the rear slot? This should balance out the box in terms of maintaining positive pressure but will having two fans on the top as exhaust and one fan on the top as intake cause issues with air flow? 

 

The picture bellow shows the fan placement and the direction of air flow for the case in question. (Placement isn't exact.)

 

My case 100% for sure supports 3 x 140mm fan on the top, 2 x 140mm fans in the front, 2 x 120mm fans on the bottom, and one 140mm fan in the rear. (I have placed a fan in every slot at one point during my build so i know for sure the case supports the fan size and positions I have indicated.

 

The 120 MM fans (bottom) each have a 50.5 CFM rating and the 140 fans (top and front) have a 60.4 CFM rating. I haven't been able to find out what the radiator fan on the video card radiator's 120mm fan CFM rating is.

 

Does anyone see a problem with the top having two exhaust and one intake fan?

[suchamoneypit]

Are you sure you can even get a fan there? it looks like the dvd bays and stuff are there, reducing width; and from my experience with cases you can't fit a fan there. 

[JefferyD90]

3 minutes ago, Gothfather said:

I have a Phanteks Enthoo pro case with two bottom 120mm intake fans and two 140mm front intake fans. For exhaust i have 3 140mm fans 2 on the top of the case one at the rear. This creates and intake of 121.8 CMF and an exhaust of 181.2 CMF. I am adding an EVGA GTX 1080 FTW hybrid video card which has a small radiator and a 120mm fan. I am pretty sure adding this 4th exhaust fan will push my case from a positive pressure case to a negative or neutral pressure case. I prefer to keep the case at positive pressure because it is in a room that gets dusty.

 

I have room for 3 top fans, 2 front fans, two bottom 120mm fans and 1 rear fan. So this radiator fan from the video card is going to fill up all my fan slots so adding a fan isn't an option.

 

So should i move the rear exhaust fan and put it in the open top fan slot and switch it to intake and add the video card radiator & fan to the rear slot? This should balance out the box in terms of maintaining positive pressure but will having two fans on the top as exhaust and one fan on the top as intake cause issues with air flow? 

 

The picture bellow shows the fan placement and the direction of air flow for the case in question.

 

The 120 MM fans (bottom) each have a 50.5 CFM rating and the 140 fans (top and front) have a 60.4 CFM rating. I haven't been able to find out what the radiator fan on the video card radiator's 120mm fan CFM rating is.

 

Does anyone see a problem with the top having two exhaust and one intake fan?

Well, according to your current description you're already at a negative air pressure rating...

 

Personally, I'd put the rad in the rear exhaust and leave it exhausting.

[corrado33]

4 minutes ago, Gothfather said:

I have a Phanteks Enthoo pro case with two bottom 120mm intake fans and two 140mm front intake fans. For exhaust i have 3 140mm fans 2 on the top of the case one at the rear. This creates and intake of 121.8 CMF and an exhaust of 181.2 CMF. I am adding an EVGA GTX 1080 FTW hybrid video card which has a small radiator and a 120mm fan. I am pretty sure adding this 4th exhaust fan will push my case from a positive pressure case to a negative or neutral pressure case. I prefer to keep the case at positive pressure because it is in a room that gets dusty.

 

 

If the bolded text above is correct you already have a negative pressure case. 

[Gothfather]

Sorry that was a typo should read 221.8 CFM intake

[Gothfather]

6 minutes ago, suchamoneypit said:

Are you sure you can even get a fan there? it looks like the dvd bays and stuff are there, reducing width; and from my experience with cases you can't fit a fan there. 

yes. The case has LOTS of clearance on the top and the case is deep so you can actually get 3 140mm fans on the top all of which sit behind the optical drive bays. I just put the arrow there so it is easy to read the pic. The arrows do not represent exact placement of the fans.

[Daniel644]

just put the cooler and it's fan as the rear exhaust, adding an intake at the top would just create lots of turbulence disrupting airflow and adding another exhaust fan would put you in negative pressure, or you could add a fan controller for the exhaust fans and slow them down so they don't move as much air if you are hell bent on adding another fan.

[Gothfather]

14 minutes ago, JefferyD90 said:

Well, according to your current description you're already at a negative air pressure rating...

 

Personally, I'd put the rad in the rear exhaust and leave it exhausting.

Made a typo on the intake CFM value corrected to 221.8.

 

In my example the rear exhaust fan is the radiator and it is exhaust.

[JefferyD90]

2 minutes ago, Gothfather said:

Made a typo on the intake CFM value corrected to 221.8.

 

In my example the rear exhaust fan is the radiator and it is exhaust.

Then you're not adding any CFM to your setup, you're probably less exhaust CFM actually, the radiator will dampen the exhaust.

[Gothfather]

3 minutes ago, JefferyD90 said:

Then you're not adding any CFM to your setup, you're probably less exhaust CFM actually, the radiator will dampen the exhaust.

The radiator will not have zero CFM however. Assuming I keep the current ratio of intake to exhaust the added exhaust radiator will be problematic. The room the computer is in is dusty (not industrial levels but dusty non the less) so positive pressure actually will help maintain the cases cooling qualities over the long run as dust will not get inside the case to reduce the efficiency of the system's heatsinks. For a radiator to be effective it requires airflow OVER the "fins" to bleed off the heat from the liquid into the air and that requires airflow which requires CFM. So adding the radiator WILL reduce the pressure, in the case how much is in question but given that a case isn't airtight to begin with and there is only 40 CFM difference currently adding a vdeo card exhaust radiator is going to drop the CFM differential by at least half if not nearly all of it. Even if the radiator reduces CFM of the fan to 1/2 of a 120mm fan, so say around 25 CFM i go from positive pressure to nearly neutral at only a 15 CFM differential between intake and exhaust, which probably isn't enough to keep dust out of the system.

 

This is why I feel i need to replace the rear fan exhaust fan with the exhaust radiator and take the now extra fan and make it an intake fan. The issue here isn't just cooling it is creating a system that cools effectively WHILE maintaining positive pressure to counteract the dusty environment the computer operates in.

 

 

 

 

[Gothfather]

30 minutes ago, Daniel644 said:

just put the cooler and it's fan as the rear exhaust, adding an intake at the top would just create lots of turbulence disrupting airflow and adding another exhaust fan would put you in negative pressure, or you could add a fan controller for the exhaust fans and slow them down so they don't move as much air if you are hell bent on adding another fan.

I already have the fans they are already in the system spinning away as I type. What i don't have yet is the hybrid video card. The video card ADDs the extra fan because it comes with a rad & fan. SO being hell bent on adding a fan is because the video card comes WITH the fan in a closed loop.

[Daniel644]

Just now, Gothfather said:

I already have the fans they are already in the system spinning away as I type. What i don't have yet is the hybrid video card. The video card ADDs the extra fan because it comes with a rad & fan. SO being hell bent on adding a fan is because the video card comes WITH the fan in a closed loop.

so REPLACE the fan on the back with the fan that comes with the cooler, just because you HAVE the fans doesn't mean you HAVE to use every one of them.

[LogicalDrm]

When you add rad+fan, remove one of top exhausts. Or both. And see how it goes. I would take less noise over more fans any day.

[Gothfather]

20 hours ago, LoGiCalDrm said:

When you add rad+fan, remove one of top exhausts. Or both. And see how it goes. I would take less noise over more fans any day.

I'll check sound levels for sure after the exchange. Good advice.

 

Currently with 7 case fans + 2 CPU fans and 2 on board GPU fans  the rig is very quiet, the hard drive is the loudest piece of equipment in the rig. At 15 cm (6 inches) above the rig the decibel output was 45, at 30 cm (1 foot) it was 40. (using a phone app to measure here so not super sensitive equipment but this gives you an idea of the sound levels.  It is raining hard outside at the time so some of the sound will be ambient rain noise.)  Right now as I type this post the rain is louder than my computer. Please note that as I am surfing the net the strain on the system is minimal so this shouldn't be take as how quiet the system is under load. i am quite please at just how quiet the bequiet! equipment is.