Question 570x fan orientation question- top intake or exhaust?

victortsoi

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So I have a 570x case running with a 360mm AIO in sandwich configuration (3x push 3x pull), rear 120mm exhaust. I have two top 140mm fans and am unsure whether to put them as intake or exhaust. CPU temps are great either way, but my main concern on the x570-e board is the nvme ssd does get pretty hot, say up to 60 + while gaming. I dont know if changing the top fans will help this much.
 

iPeekYou

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360mm rad is in front, there are 3 front intake fans in front of it, and 3 exhaust behind it, so fan->radiatior->fan into the case.
60ish degrees is fine, IIRC 70 degrees is maximum operating temperature. I thought NVMe SSDs have a thermal throttle safety? I don't have one myself, just remember I read that somewhere. My guess is your GPU is radiating heat to the SSD, assuming it's mounted between CPU and GPU like they usually are.

If you're that concerned, maybe get an active NVMe SSD heatsink with a tiny fan. I find a few available locally for $15 or so. Maybe also try running games with side panel open. If you're lacking airflow around the NVMe slot, this should reveal that need. The janky solution to that problem is jury rigging a case fan inside to blow air near the SSD towards the back of the case.

Also to answer the original question: most of the time, you don't want top fans as intake. Heat rises, yes, but airflow trumps that effect. The thing is top fans as intake, ceteris paribus, will disrupt the general airflow. Temps are more dependant on flow rather than sheer volume (well, mass, actually) of air being introduced into the case.
Not to mention top fans are too far from the NVMe slot to do anything IMO. There's also the risk of pushing GPU heat downwards back to the GPU too.
 
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Phaaze88

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Top intake can work, but it depends much on how the gpu is being cooled.
-Turbo/blower
-Hybrid
-Custom liquid
If it's not one of the above, forget top intake.
Some chassis are so badly designed that top intake actually works over the usual top exhaust! The X570 Crystal isn't one of those, so don't worry about that.

I thought NVMe SSDs have a thermal throttle safety?
They do, but since they're already 'blazing' fast, you won't really notice lost performance unless you specifically look for it, like in benchmarks.
Though it seems the Gen 4 ones get pretty bad to the point of stuttering...
 
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iPeekYou

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Top intake can work, but it depends much on how the gpu is being cooled.
-Turbo/blower
-Hybrid
-Custom liquid
If it's not one of the above, forget top intake.
Some chassis are so badly designed that top intake actually works over the usual top exhaust! The X570 Crystal isn't one of those, so don't worry about that.
Yeah, I figured most people will have an open GPU instead. Blowers are getting more scarce, and liquid cooled ones are rare as they are.

Bit of a hijack, but what kind of case would necessitate top fans as intake? Bad front airflow?
 

Phaaze88

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Bit of a hijack, but what kind of case would necessitate top fans as intake? Bad front airflow?
Yes.
You know how the closer a fan is to a solid surface, the less air it can move? Or how a fan draws in air in a conical shape, but solid surfaces all up in its face completely disrupts that?
Yeah... some of them have the fans and front panel so close to one another that any little side vents on the side do next to nothing.

Yes, the silence focused, silence marketed - whatever you want to call it, silence-something... they're going to make a little less noise, and the dust volume over time is a little lower too, but that's paid for with higher thermals.
It can kind of be brute forced with some liquid cooling, since liquid has higher thermal tolerances, but the radiators still need air to go through them and what not - it'll still warm up there, but it'll take longer with liquid.
 

Karadjgne

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Airflow characteristics define fan orientation. Raijintek has a couple of smaller mBTX cases that have a rotated motherboard. That puts the gpu on top - upside down. The gpu fans pull air into the gpu, and with it so close to the lid, if you used exhaust on top, the gpu would get almost no air at all. So top fans there are best as intakes, blowing directly onto the gpu.

Some cases have such abysmal front intake availability that a top-front intake and top rear/rear exhaust are beneficial just for the cpu aircooler and airflow from the gpu area is guided by pressure from the top intake towards the rear top corner.

Front in, top out is a general rule, it applies to most in varying degrees, but is not the best for every case design.
 

iPeekYou

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Yes.
You know how the closer a fan is to a solid surface, the less air it can move? Or how a fan draws in air in a conical shape, but solid surfaces all up in its face completely disrupts that?
Yeah... some of them have the fans and front panel so close to one another that any little side vents on the side do next to nothing.
That's what I figured. OP's case is bit in-between it seems; front tempered glass panel but with a small space for airflow. If the gap is like an inch or so, seems fine to me. I had a case like that and tinkered with spacing, found that about 2cm of space is good enough for airflow that removing the panel completely nets only a further 1°C.

Airflow characteristics define fan orientation. Raijintek has a couple of smaller mBTX cases that have a rotated motherboard. That puts the gpu on top - upside down. The gpu fans pull air into the gpu, and with it so close to the lid, if you used exhaust on top, the gpu would get almost no air at all. So top fans there are best as intakes, blowing directly onto the gpu.

Some cases have such abysmal front intake availability that a top-front intake and top rear/rear exhaust are beneficial just for the cpu aircooler and airflow from the gpu area is guided by pressure from the top intake towards the rear top corner.

Front in, top out is a general rule, it applies to most in varying degrees, but is not the best for every case design.
True, I just keep thinking about a typical tower case with at least 2 fans up front and one rear exhaust, with a side vent at the front or just straight mesh panel.

I do agree top intake is beneficial; but in edge cases where traditional front to back, bottom to top airflow isn't viable somehow.



OP, FWIW I tried putting fans as intake on my top mounts. Found out that top rear causes higher temps on VRM, and top front doing nothing. However, this is done with an AIO cooled GPU. YMMV, but I hold the opinion that unless there's a need for it, top intake is bad idea.
 
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DSzymborski

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Yeah, generally you only see top intake as making sense for particularly unorthodox cases. Some people will make too much out of "hot air rises" which is true, but the local fan dynamics tend to overpower changes in air density. The GPU tends to be the biggest problem there; with the airflow going straight up through the GPU in the vast majority of cases, most cases will have a problem with top intake. And the top is simply a better exhaust area given traditional layout of the parts. Like even if you have a liquid-cooled GPU, you probably have a lot less clearance at the bottom of your case than the top. And front exhaust can create an environmental issue as you're more likely to be sitting in front of your PC than behind it.

But again, that's not to say that a top intake is never a good idea. In some cases, you're forced to because the case is a coffin otherwise. Some cases, especially small form factors, will have GPUs in non traditional areas. And some larger cases will have vertical GPU mounts.
 
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Karadjgne

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Good airflow is like a wide, deep river. Comes in, goes out, nice and smooth. Doesn't have to be fast, it just has to move well in continuity. That's the design of the typical case, air in front, picks up heat along the way, goes out the back.

If you've ever seen 2 rivers come together, it's a mess. Nothing but turbulence, water flying every which way, shifting currents, eddys, undertow etc. That's generally what happens when putting too many fans in odd places. A side intake might seem like a good idea, might even drop the gpu a few °C at loads, but the end result is a circulatory airflow that's dumping/pushing gpu heat back towards the intakes. This raises case temps over time, which ends up affecting the cpu, Northbridge, Sata chipsets, drives etc.

Most reviewers, even the pros, are guilty of neglecting that, their focus being on more immediate concerns with the cpu and gpu only.

If you game hard for 3-5 hrs or so, use gpu rendering, folding@home etc, a 10minute heat test is meaningless, your concern is long time affects and will that affect overall performance or even component longetivity. A 10 minute test that allows a pcie4.0 nvme to go from 50°C to 51°C is nothing compared to airflow that allows that same drive to go from 50°C to closer to 80°C after 4 hrs.

Universal law states that things are governed by equal and opposite reactions. Changing fans to help lower temps on one component means a different components temps will rise in proportion. You may not see it, but believe that the pc will.
 
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iPeekYou

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Good airflow is like a wide, deep river. Comes in, goes out, nice and smooth. Doesn't have to be fast, it just has to move well in continuity. That's the design of the typical case, air in front, picks up heat along the way, goes out the back.

If you've ever seen 2 rivers come together, it's a mess. Nothing but turbulence, water flying every which way, shifting currents, eddys, undertow etc. That's generally what happens when putting too many fans in odd places. A side intake might seem like a good idea, might even drop the gpu a few °C at loads, but the end result is a circulatory airflow that's dumping/pushing gpu heat back towards the intakes. This raises case temps over time, which ends up affecting the cpu, Northbridge, Sata chipsets, drives etc.
Yup. Flow is king, volume is a distant second. Case airflow is difficult to theorize given the turbulence from fans and the compressible nature of air. Technically, you need the mass of air to act as thermal mass, but since a) air is compressible, and b) density is a function of temperature, it's really a mess to say the least. Volume is easier to discuss since it's a given with X amount of space inside the case, and Y airflow at any given time.

As such, top intake is unorthodox; it disrupts the traditional front to back airflow, and only to be used in cases (heh) where front intake is suboptimal. A case with good mesh front, or at least an inch of clearance from the front of the fan to the solid front panel is enough. Top intake isn't inherently bad, it can be made to work especially if there's a good path for airflow towards the bottom, in theory. Its close proximity to the hot components can make it work, but with no good flow for the air from the top to go, it's difficult to justify.

Furthermore, generally, exhaust is better than intake for removing heat. It's bad for dust prevention, but with some airflow (discounting tiny vents or gaps in panels), exhaust is still better for removing heat. You can get much more mileage out of a good fan as exhaust compared to as intake.

Really, one or two fans with minimal obstruction as intake is good enough. Most of the time even the top fan on a 3-fan front panel is doing nothing. It's just there to give a little bit of flow towards the exhaust at the rear. Basically, the front fans are doing just that; directing flow. With good panel or gap up front, I find it's nearly no difference in temps between bargain bin fans ($2 LED ring fans) up to Corsair SP120 PE (the old ones).

Bit-tech's article also covers this as well, and they're pretty thorough with including chipset ( I guess representing other components) temps as well. I concur with their conclusion of leaving top as exhaust at the rear mount, and leave the front mount open (or seal it if you can). Adding intake at front top directly disrupts intake from front fans, and top rear as intake makes little sense in most use cases.


To add a bit: side panel intakes are similarly on edge case use. If you have poor airflow near the GPU area, then yeah, it'll help. If you already have good flow from the front, then there's zero use for it. I had a case with 3x front fans that I replaced the front and side panel with custom acrylic panels. The one in front has cutout for the 3 fans so no obstruction from the panel itself, and the side panel has 2x 120mm mounts with holes for ventilation. I found that the side fans do nothing at all, in intake or exhaust. There's barely a degree of difference between no fans, fans as intake, and fans as exhaust. FWIW, one side fan towards the rear as exhaust is good for a degree C that is consistent in my tests.

Good for old cases with a single intake: 1 120mm fan that's also cooling harddisk or what have you, not so useful for recent cases with modern sensibilities.
 

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