Help with Cooling

StumpyJake · 6 Aug 2015 at 16:23

Hi,
I'm just about to embark on my first build for a long time and need some advice on cooling. My case is a Phanteks Enthoo Luxe and I have gone with air cooling throughout as I was a little hesitant on putting a water cooling loop in for the first time. Also the GPU I have got, Palit GTX 980ti Super Jetstream, doesn't allow for the removal of the stock cooler as far as I know. Anyway fans it is. The PC was going to be resting on a carpet but I have now designed and built a stand that will raise it about 12cm from the floor so I can get some air underneath the case. Generally the cooling I have come up with is the same, the only questions I have are around the CPU cooler direction and the PSU direction

In general I have two additional 140mm Phanteks PH-F140SP fans to the top of the case as exhausts, one was already installed. The rear exhaust fan I assume is the same type, 140mm Phanteks PH-F140SP. The front intake is stock a 200mm PH-F200SP and in the bottom I'm adding an additional 140mm Phanteks PH-F140SP as a intake, (reason for the stand to raise the case off the carpet).

My query is:

A) - what to do with the CPU cooler, this is a Phanteks PH-TC14PE and has 2 PH-F140 fans. Do I point the cooler fans towards the top exhaust fans or, what seems to be the norm, towards the back at the rear exhaust. My worry is that if I point it towards the top exhausts it will be sucking hot air from the back of the GPU through the CPU radiator. I'm not sure if hot air cools when being pushed through fan blades, like it does with a household fan.

B) - The PSU fan should I have this facing the bottom of the case sucking cool air from underneath where it will exhaust out the back? I will be leaving the PSU cover in place so if I point it facing inside the case it won't be getting any cool air, except only from the bottom 140mm fan I will be installing which sits near the end if the PSU cover.

Anyway any advice will be much appreciated. Last time I built a PC you didn't have to worry about all this cooling stuff, how times change...

Thanks in advance.

Hagar · 6 Aug 2015 at 16:47

A) Towards the back. I used this successfully. It may need lifting the fan above the ram 10-15mm or using low profile ram or as I did remove the heatsinks.

B) Fan in bottom of case. Do you have a filter in place. If not and it is on carpet, a tile or piece of ply or plastic will stop fibres being lifted.

Hope this helps, andy.

StumpyJake · 6 Aug 2015 at 16:58

Hi Andy,
Thanks for your input. I have got fairly low profile RAM so it should sit below the cooler OK. I think Phanteks say anything less than about 32mm should be fine although the fans on the cooler can be raised a little. As for the PSU as I mentioned in my post I have built a stand which raises the case 12cm from the floor and it has a solid base. I also have filters on the bottom so hopefully it will be OK.

doyll · 7 Aug 2015 at 21:46

I would suggest moving the 200mm fan to the top and put 2x PH-F140SP fans in front as intakes. Ideal airflow is front to back with as little bottom to top as possible. This is because the GPU cooler dumps heat everywhere and front to back flow move it back and out of case without mixing and heating up the CPU cooler's intake airflow.

StumpyJake · 12 Aug 2015 at 13:56

Hi Doyll
Thanks for that

PieEater · 12 Aug 2015 at 16:56

A household fan or any fan does not make the air cooler, moving air allows heat to be displaced more effectively from the heat source. With humans the cooling effect of a fan is provided by better evaporation of our sweat not through magic fan blades that turn hot air to cold.

Doyll is right to point out that your graphics card cooler is going to provide a flurry of heated air in the middle of your case. Consider though that hot air rises so it is inevitable that this is going to be fed to your CPU cooler. I would argue that a bottom intake may be useful not only in providing cool air to your graphics card but also in directing the heated air to the top of your case and the exhausts. The best approach depends on a lot of variables so it is normally trial and error until you find what works best for you. I find it helps to visualise the air inside the case as water with a natural inclination to work its way upwards and to think about how the optional fans would assist this process and work in conjunction with the GPU and CPU coolers.

doyll · 12 Aug 2015 at 18:11

Still air warmer than surrounding is less dense and will rise .. until you add a fan. Than the fan overpowers any effect the pressure differential between warn and cool air has.

Therefore "hot air rises" is not true in our computer
systems.

My thoughts are that we do not what conflicting airflow in the case. This causes turbulence which allow warm exhaust air to mix with cool intake air. The more direct the airflow is from front to back the better. In some cases replacing 3x 5.25" front bays with a intake vent and fan will give straight line airflow to CPU cooler and straight out the back vent .. and works very well if it can be done.

Enthoo Luxe has a pretty well vented back, In reality 2x 140mm front intakea and 1x bottom intake with no top fan at all will cool most builds very nicely.

I plan to experiment with my Luxe and see what airflow temps do when block the top vent for better front to back flow. In my old Define R2 (w/ 2x 140mmfront intakes and 1x 140mm bottom intake) having the top vents closed off give better cooling.

Airflow is fluid dynamics,

I use a simple indoor / outdoor digital thermometer with hardwired probe to monitor temps of airflow inside of case. It's often amazing how cool spots and hot sport are where we would least expect them to be.
http://forums.overclockers.co.uk/showpost.php?p=26159770&postcount=7

PieEater · 12 Aug 2015 at 19:31

doyll said:
Still air warmer than surrounding is less dense and will rise .. until you add a fan. Than the fan overpowers any effect the pressure differential between warn and cool air has.

That is purely dependant on what speed "The Fan" is running at, what pressure it is producing, and where it is positioned, it is impossible to state this as fact. I would argue that very few people would want a fan that potentially trapped hot air in their system by preventing it from rising to the exhaust fans which are inevitable at the top of the case, or would tolerate the noise generated by such a fan.

"hot air rises" is not true in our computer systems.

Hot air rises is true inside or outside of our computer systems, it is a law of thermodynamics which may be possible to temporarily bypass through introducing barriers, but why would you want to create pockets of warm air inside a computer case when the goal is to eliminate this. My thinking is that it would be better to work with nature and encourage the hot air upwards and out through the exhausts.

My thoughts are that we do not what conflicting airflow in the case. This causes turbulence which allow warm exhaust air to mix with cool intake air.

But the OP already has conflicting airflow, horizontal turbulence from his graphics card and vertical turbulence from his CPU cooler. This is not an ideal situation and as I have suggested he needs to experiment to see what gives the best results.

Airflow is fluid dynamics,

I felt given the contents of his post the OP would benefit most form an illustration of fluid dynamics rather than being told what the principle was called.

I use a simple indoor / outdoor digital thermometer with hardwired probe to monitor temps of airflow inside of case.

It's this level of detail that makes me respect your input into these forums and I hope you don't mind me playing devils advocate.