Optimal no. of fans?

[plissk]

Looking for the best low noise/high performance balance for my Fractal Design R5 case. Z370 mobo, Gigabyte Aorus RX570 4G GPU, Removed HDD cages, retained optical drive cage. Corsair H115i with 280mm radiator in front with stock Corsair fans in push (in) config (to cool an i7 8700k). Corsair RM650x PSU on bottom of case. 1 stock FD dynamic gp-14 fan in bottom middle intake. 1 stock GP-14 exhaust fan in upper rear. Have 2 Samsung NVMe drives, one in M2M slot and one in M2P slot between PSU and GPU. Will be upgrading to Phanteks PF-H140XP fans to replace the FD fans. Do I need any more fans? If so, where? Temps don't seem to be excessive but I'm not pushing the machine much atm and am rather new to this, and I hear reports of the Define R series cases not having great air flow with just 2 stock fans.

I could install an additional fan in the bottom (intake) and/or an additional fan on the side panel. Room on the bottom is a bit tight with the 280mm radiator as it goes all the way to the bottom of the case. I have room for the existing 140mm fan and about 100-110mm spare next to that, so a 92mm fan might work there (e.g. Noctura NF-B9 redux-1600 PWM). There are a load of power cables coming out of the PSU which eats into the '140mm' space next to it, so it might be best to move the existing 140mm fan across nearer to the radiator to give it clear air above it and either leave an empty gap in between or put the 92mm fan there, away from the overhead power cables. If I was to use the side panel fan slot with a 140mm fan, I'd be inclined to use it as an exhaust rather than intake as otherwise it will pull dust into the case (the filters you can buy can only be changed or cleaned by removing the fan each time which is a pain in the neck).

Another alternative is to put 2 x 140mm fans behind the 280mm radiator in the front so I have better (warm) air flow coming from the front of the case from the radiator (push/pull) and slightly better CPU cooling). I am however conscious that I really only have one intake fan pulling in cool air.

I have 2-3 slots available in the top of the case but I figured I'd rather not use them unless I really needed to, to a) reduce amount of dust getting into the case when the machine is off and b) to reduce noise.

Any input is appreciated! Cheers.

Update: Pics here https://pcpartpicker.com/b/3TzYcf

 

[Zerk2012]

Those FD fans are good just add anouther front 140mm for the parts your using their no reason to fill the case up with fans.

 

[plissk]

Those FD fans are good just add anouther front 140mm for the parts your using their no reason to fill the case up with fans.

Thanks Zerk. I removed the stock FD fan from the front and put it on the bottom (intake) as I put a 280mm radiator up front (with 2 Corsair fans as push intake), so case front is more or less full up. U think that is enough?

 

[SkyNetRising]

I don't think there's any need for more fans.
Probably 2x140mm front intake (on radiator) and 1x140mm rear exhaust fans would be enough.

If you could attach a photo of inside view of your system, that would be great.

 

[Zerk2012]

I don't like blowing warm air in a PC but I dont think the 115i will fit in the top of the case.
It should be fine as it is with the 140 in the botton.

 

[plissk]

Thanks for the responses. Here is my build inc. pics. I will try to incorporate it into my sig.

https://pcpartpicker.com/b/3TzYcf

 

[AniChatt]

Thanks for the responses. Here is my build inc. pics. I will try to incorporate it into my sig.

https://pcpartpicker.com/b/3TzYcf

Install the rad in front of the case to intake cool air (much better cpu cooling) and exhaust it from back fan. You can install one extra fan on top extreme back of the case as exhaust only. As per my understanding and knowledge adding any more fan will not going to give you any tangible benefit. Moreover don't even think to add another fan from bottom intake near the psu and also in the side panel. try to maintain neutral air pressure if not possible +ve air pressure becs it will help to reduce dust inside case and cooler system.
Now front intake rad may increase the gpu temp but trust me it will not be that huge. You will get a cooler CPU which eventually lead to less noise as rest of the fans will be connected on the mobo and controlled by the cpu temp. If you change the rad config to be cooled by the exhaust air it will increase the cpu temp and automated fan control will kick in.However the gpu temp will be a bit on lower side. But if you compare these two scenario using rad with a intake fan is much better.
Lastly say as per your work load, if the gpu will stay at 100% most of the time and cpu will be in say 20-50% then exhaust rad config will be a bit better to balance overall system temp. Now if both will be in a good use then again use cpu rad as intake. If you don't believe, just give it a try.

 

[plissk]

Install the rad in front of the case to intake cool air (much better cpu cooling) and exhaust it from back fan.

Thanks for the input. Do you mean locate the radiator physically outside the case at the front (removing hinged front panel), or inside the case at the front (behind the fans, like I have in my pics)?

I saw a youtube video (LinusTech?) where the overall conclusion was that 2 fans gave the most benefit to cooling and adding additional fans achieved only marginal improvements. However, the front of the R5 case is restricted by the thin slits in the side of the front panel and the dust filter. Dust filter on the bottom and mesh grill also restrict airflow.

I was thinking that if adding more intake fans doesn't improve airflow that much, then adding 2 more fans behind the radiator to achieve push/pull would at least help lower CPU temps more tangibly.

 

[AniChatt]

Install the rad in front of the case to intake cool air (much better cpu cooling) and exhaust it from back fan.

Thanks for the input. Do you mean locate the radiator physically outside the case at the front (removing hinged front panel), or inside the case at the front (behind the fans, like I have in my pics)?

I saw a youtube video (LinusTech?) where the overall conclusion was that 2 fans gave the most benefit to cooling and adding additional fans achieved only marginal improvements. However, the front of the R5 case is restricted by the thin slits in the side of the front panel and the dust filter. Dust filter on the bottom and mesh grill also restrict airflow.

I was thinking that if adding more intake fans doesn't improve airflow that much, then adding 2 more fans behind the radiator to achieve push/pull would at least help lower CPU temps more tangibly.

Inside the case as intake. Cooler air used for cpu cooling.
No problem with dust filter in front. Keep it there don't remove it. And push pull on that thin rad like that you don't get big difference. On my h80i having double thick rad the temp reduction is 3c in push pull compared to push.

 

[plissk]

Inside the case as intake. Cooler air used for cpu cooling.
No problem with dust filter in front. Keep it there don't remove it. And push pull on that thin rad like that you don't get big difference. On my h80i having double thick rad the temp reduction is 3c in push pull compared to push.

Thanks for clarifying. Yeah your H80i is 38mm thick vs my H115i 26mm so I guess that's nearly 50% thicker, and your fans are 120mm via my 140mm diameter (although both rated at 4mm H2O) so push/pull makes more sense with your radiator probably. Haha no I wasn't going to remove either dust filter, dust avoidance is a priority for me, part of the reason for getting this case. Cheers.