Well no, I did not say that he had "every fan acting as reverse" either.

 

below fooled me. Fair enough if that's not what you meant.

 

 

After this it's logical to have every other fan acting as exhaust, lowering the overall case pressure and assisting CPU radiator intake.

 

 

onebob says he has his CPU water cooler fans exhausting.

 

Yes, I misread that, he said "2 fans on top of case ( water cooled stuff) air coming out and upward"

 

 

 

Presumably the case builder has given priority to CPU cooling and set up the rear fan as an intake to assist the outflow of the CPU radiator fans and provide it directly with cooler outside air.

Looking at his photo of the case internals you can see that he has a very large rear fan sitting very close to his CPU fans. Running the rear fan as exhaust could slow CPU air flow, at least through the closest CPU fan.

 

 

Correct, but as I said, this still isn't' the norm, or conventional wisdom. The vast majority of builds with a closed loop cooler on top, fans set up as exhaust, will still favour a front to back airflow configuration. Namely a couple of fans [or more] at the front blowing in, AIO cooler fans at the top out, and rear fan out. Yes it can be configured differently, but as I say, it's not the norm.

 

 

 

. Running the rear fan as exhaust could slow CPU air flow, at least through the closest CPU fan.

 

 

I see your point, but would have to disagree. The airstream from two or more front fans, would be perfectly capable of feeding both an AIO coolers fans exhausting, and a rear fan exhausting. From what I know about fluid dynamics, the airstream is perfectly capable of diverting and feeding two AIO fans and one rear fan equally. I don't see that there would be any appreciable  impact on the AIO fan closest to the rear fan. All three fans [as long as they are similar in performance] would exhaust equally. By your logic, the front closed loop cooler fan would slow the airflow of the rearmost closed loop cooler fan... clearly that doesn't happen.

 

Put another way, by your logic, if a rear fan impacts an adjacent radiator fan, then the adjacent radiator fan should also impact the rear fan, thus... balance!

 

The only way I can see that happening is if the rear fan [as an exhaust] has a much higher rpm and thus exhausts greater CFM than the AIO fan. In that out of balance arrangement then yes, the closed loop coolers fan may be impacted. In reality of course that's not the case. If all three fans are of equal capability then airflow is diverted equally.

 

But as I say, my point was merely that a rear fan as intake isn't the norm, that's all.

 

below fooled me. Fair enough if that's not what you meant.

 

 

 

 

 

 

Yes, I misread that, he said "2 fans on top of case ( water cooled stuff) air coming out and upward"

 

 

 

 

 

Correct, but as I said, this still isn't' the norm, or conventional wisdom. The vast majority of builds with a closed loop cooler on top, fans set up as exhaust, will still favour a front to back airflow configuration. Namely a couple of fans [or more] at the front blowing in, AIO cooler fans at the top out, and rear fan out. Yes it can be configured differently, but as I say, it's not the norm.

 

 

 

 

I see your point, but would have to disagree. The airstream from two or more front fans, would be perfectly capable of feeding both an AIO coolers fans exhausting, and a rear fan exhausting. From what I know about fluid dynamics, the airstream is perfectly capable of diverting and feeding two AIO fans and one rear fan equally. I don't see that there would be any appreciable  impact on the AIO fan closest to the rear fan. All three fans [as long as they are similar in performance] would exhaust equally. By your logic, the front closed loop cooler fan would slow the airflow of the rearmost closed loop cooler fan... clearly that doesn't happen.

 

Put another way, by your logic, if a rear fan impacts an adjacent radiator fan, then the adjacent radiator fan should also impact the rear fan, thus... balance!

 

The only way I can see that happening is if the rear fan [as an exhaust] has a much higher rpm and thus exhausts greater CFM than the AIO fan. In that out of balance arrangement then yes, the closed loop coolers fan may be impacted. In reality of course that's not the case. If all three fans are of equal capability then airflow is diverted equally.

 

But as I say, my point was merely that a rear fan as intake isn't the norm, that's all.

 Thanks for the input on this everyone,  It may be they adopted this method as the case (Fractal Design Define R4 Black) has a door on the front therefore no access for mounting any fans.

With the side access panel off its seems to be good air flow above the GPU, however below it doesn't and feels much warmer. of course this area is adjacent to the PSU and the fan for the GPU.

There is an option for a additional fan on the removed side panel in the bot 1/3 and towards the rear.

 

bob

It may be they adopted this method as the case (Fractal Design Define R4 Black) has a door on the front therefore no access for mounting any fans.

I thought it had an option for two fans at the front, one included, air being fed to those fans from the vents on the side?

 

 

https://www.google.co.uk/search?q=fractal+design+r4&espv=2&biw=1024&bih=667&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiUuZbdou_JAhVFlQ8KHWJ9BJkQsAQILA#imgrc=bIQnnhuqDGld2M%3A

 

 

 

 

Apparently the Define R4 has...

 

 

 •Front: 1 - 120/140mm fan (included is a hydraulic bearing 140mm Silent Series R2 fan, 1000 RPM speed; 1 - 120/140mm fan (not included)

 

•Rear: 1 - 120/140mm fan (included is a hydraulic bearing 140mm Silent Series R2 fan, 1000 RPM speed)

 

•Top: 2 - 120/140mm fans (not included) - positions also support some models of 240 radiators, depending on configuration

 

•Bottom: 1 - 120/140mm fan (not included)

 

•Side: 1 - 120/140mm fan (not included)

 

•Fan controller: 1 - Integrated fan controller for up to 3 fans (included)

 

 

http://www.fractal-design.com/home/product/cases/define-series/define-r4-black-pearl

 

 

The important thing is your temps Bob. If your components are running within safe temps it's not a worry and you shouldn't be concerned. Optimising cooling is always worthwhile though.

 

My preference for the Define R4, would be a couple of fans at the front blowing in, and I would definitely remove any hard drive cages not being used, so they don't impede air flow.

 

At the end of the day it's about personal preference, whether you prefer a positive, balanced or negative case pressure.

 

There are lots of option. In fact Corsair recommend that their AIO water coolers are configured so that the fans suck cool air in from the outside and into the case. This way cool outside air is cooling the radiator. Of course, with this configuration you are also blowing warm radiator air into the case. Some adopt Corsairs advice, some prefer the reverse, namely warm air from the enclosure cooling the radiator and exhausting outside. Personal preference, but with a radiator there's always a compromise.

 

It's also worth remembering that in your case, if the rear fan is indeed blowing into the enclosure, then it's not filtered air, so you are also blowing dust in.