Trying to get good airflow and positive pressure

D

Dermen

Limp Gawd
Joined
Oct 10, 2017
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I have a Zalman Z12 case and my video card has always run on the warm side. It came with a 120mm intake on the front and a 120mm exhaust on the rear, they both ran around 1000rpm.

I got some fans to try and improve airflow (not the greatest fans but they were free).
(1) 120mm 3 pin 1600rpm 63cfm Scythe S-Flex
(2) 120mm pwm 1500rpm 63cfm Rosewill RWC-1612
(1) 140mm pwm 1300rpm 89cfm Rosewill Hyperborea

My case has two top fan mounts, 1 rear fan mount, 1 bottom fan mount, 1 front fan mount, and empty 5.25 bays. They are all 120/140mm except the rear is 120mm only. The top and front are mesh and the entire front has dust filtration. I have a Thermalright tower cooler with a single 120mm pwm 1300rpm 58cfm Thermalright fan.

I put the 120mm Scythe on the rear as exhaust, the 120mm Rosewills on the bottom and front as intakes, and the 140mm Rosewill in the 5.25 bays as intake. At full speed the fans are moving a decent amount of air and I thought this would give me lots of positive pressure. I can feel air blowing out the back of the case below the video card (the pci slot covers and the area next to it are mesh). The confusing part to me is air is being pulled into the case through the top fan mounts. Not a lot but if you hold a piece of paper just over the mesh it will get sucked down. This is with all fans on full when running P95. If I limit the exhaust fan a little bit the top opening appears to be neutral.

The case is not great for airflow. The front intake was ridiculously restricted. Air goes through the front mesh, then a thin airy sponge like filter, then a plastic dust filter, then honeycomb mesh before it reached the fan. After the fan it goes through honeycomb mesh twice more (HDD bay, at least they are mesh instead of solid) then it was blocked by a solid piece of plastic that would snap the HDDs in place so they could be tool less. I removed the plastic filter and cut out the honeycomb mesh in front of the fan. I also removed the plastic tool less HDD thing since it also has a place to just use a thumbscrew instead. The buttom PSU intake seems even more restrictive, so much so that it seems almost useless.

My next adjustment will be mounting the PSU fan up. I think I will swap the Scythe and 120mm Rosewill as well to get more intake to counter the PSU exhausting case air.
 
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I'd mount the PSU fan down, that way it's in taking fresh air from the outside (assuming your case has decent room under it) and exhausting it out the back so it's not using case air at all.

I'd also take the fan on the bottom and put it up top as an exhaust. I've found bottom fans help a little but not enough to make it worth messing with them, at least not in my experience.

And you can always just take the side of the case off and leave it off. I leave the side of my 500R off for cooling but also because I like seeing the components. May not be the best looking way but I like it.
 
You can see a pic of the bottom of the case here. My PSU is short so a few of the slots aren't under the fan. The PSU was very warm after gaming for a few hours the other day, it's case felt just as hot as my 980ti backplate. The graphics card was hitting 83C and lowering boost clocks which is what started this whole thing. I would cut out the slots so it was all open but I don't want to pull everything from the case, maybe next time I upgrade my MB. It's fully modular so it will be easy to flip and test.

I do have another fan and 1 spare fan header I was going to test as a top exhaust. The fan is 2000rpm and not PWM so it is loud at idle. I was afraid it would cause negative pressure too.

Leaving the side off is no good. There are too many LEDs and it is next to my TV, I need to keep it on to block all the light.
 
Why I Haven't been running in a case too, runs Hotter and louder got to Hot box the front and a high flow exhaust....talking like louder 2500rpm+ for exhaust and those are all kinda pretty loud. Everything in there I swear runs 5-10 degrees hotter easy.
 
I did some testing today and I probably need to run my tests longer. I tested with the 3 Rosewills as 2 front, 1 bottom intake and the Scythe as rear exhaust. Then I moved the bottom intake to top exhaust as MacLeod suggested.

I ran P95 for 10 mins, then Heaven benchmark with fans on low, then Heaven again with fans on high. Temps were within 1 degree on all tests. I did low and high speed fan test in Heaven because the CPU doesn't get hot enough to ramp up the case fans. The Heaven temps were 4-5 degrees cooler than with the old fans I removed.

Hopefully I get some gaming in today to get a real world test.
 
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