[SOLVED] 400D with H115i, how to setup fans properly?

terragady

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Hi,

I have a 400D case and H115i water cooling for my CPU. I have bought few noctua fans to replace the H115i ones, also one for top and one on the back. The original one from H115i is on top as well connected to CPU OPT and set to 20% all the time due to noise reduction.

I have also 2x HDD, 1x SSD, Asus GTX 1080 ti and Z370-f mobo.

The intake fans are only the ones attached to radiator. The problem is with HDD temps and GPU temps when on load. It seems there is not enough cooling inside. I have set the intake fans to not go below 50% any time and it helped a bit(they are still silent at this RPMs). They actually barely go any above that because liquid does not get hot even on higher CPU temps.

I was thinking that I can change the top Noctua fan (the one more on front) to the intake as well so it will blow to GPU and HDDs but will cross with the stream from front fans. Even maybe connect it to GPU output or set it to fixed RPMs. Maybe setting a GPU fans to not stop on idle would also help with air circulation? What do you think?

https://i.imgur.com/z17YMBc.jpg
 

Aeacus

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There are no Corsair 400D PC case, what there are, are: 400C, 400Q, 400R, 450D. Yours seems to be either 400C or 400Q.

As far as your cooling issue goes, make a simple test:
* pull the solid front panel off the case and look if you still get high internal temps.

Btw, which model Noctua fans you have?
 

terragady

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yes sorry, it is a 400C, fans are nf a14 and nf f12
Yes I have tried removing it and a dust filter too but same result. The problem is not the cooling of radiator as my CPU is all fine with temp and a liquid in radiator after gaming is not more than 35C.
 

Aeacus

Illustrious
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I was wondering if the solid front panel would hinder the frontal airflow, resulting in higher GPU and HDD temps but as witnessed, the rad alone is enough to handicap frontal intake.

In this case, mount your rad as top exhaust. This way, frontal intake wouldn't be handicapped by the rad and you'd have much better air intake. Also, with rad as front intake, all the heat CPU produces are pulled into your PC and directly onto the GPU. With rad as top exhaust, CPU heat would be directly exhausted outside of the case.

2nd option would be creating higher negative pressure inside your PC case. To do that, you'll need to run your 2x top and 1x rear exhaust fans much faster than you run your 2x intake fans. Positive side of negative pressure is that all the hot air generated inside the case would be expelled as soon as possible. Negative side of negative pressure is that you'd get more dust intake since each and every case opening would then be intake (more places for dust to enter).

Oh, what are the actual GPU and HDD temps? Both idle and under the load?
 

terragady

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It is not possible to install radiator on top, not enough space for it, I tried. If I run my rad fans more aggressively the temps are fine but then there is quite a noise from them. They do not blow a hot air, as I said liquid is top 35C when gaming or benchmarking for long time, for short time it is 30-31C.
My HDD is getting above 40C temps.

So do you think the negative pressure will cool better than positive pressure if I will invert the top fan? Then there should be less dust, more fresh air to the GTX metal plate and HDDs. The excess will go out by the back grill and 2 left exhaust fan.

GPU idle is 40-45, the 3.5" 2T HDD is getting more than 40 (even up to 45), SSD is not getting below 40 and it has a heatsink with the PCH. When I run front fans more aggressively, gpu is 35, hdd even 31 and ssd 37. When gaming my GPU is getting up to 80, where in open case it sits around 70-71. HDD is similar on idle and load but when doing some heavy stuff on HDD it stays around 45.
 

Aeacus

Illustrious
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Yeah, your temps are relatively high, especially GPU since most GPUs thermal throttle above 80°C.

Since hot air rises, case's airflow rule of thumb is: front & bottom - intake; top & rear - exhaust.
And about airflow pressure (positive, neutral and negative), there are pros and cons with each one of them:

Positive pressure (higher air intake than air exhaust)
Pros
Less dust enters the system
All case openings contribute to getting heat out

Cons
Less cooling than negative or neutral pressure
Can create stagnant air inside the case which causes internal temps to rise

Negative pressure (higher air exhaust than air intake)
Pros
Better cooling than positive or neutral pressure
Amplification of natural convection

Cons
More dust enters the system
All case openings contribute to the air intake

Neutral pressure (same amount of intake and exhaust)
Pros/Cons
Between the two above

Further reading about setting up airflow: http://www.tomshardware.co.uk/faq/id-1858957/airflow-101-setting-fans-keeping-computer-cool.html

I run my Skylake and Haswell builds (full specs with pics in my sig) in negative pressure for optimal cooling. Since i have all intake holes and grilles covered with Demciflex filters, there's no problem for dust entering my systems.

When it comes to the PC cooling, you can't have both at the same time: good airflow and low noise. Either it's good airflow with high noise OR bad airflow with low noise. Though, there are fans out there that struck near perfect balance between good airflow, good static pressure and relatively low level of noise. But those fans come with premium price and question here is if you're willing to pay the price.

So, to increase negative pressure in your setup, run your intake fans at max 50% while running your exhaust fans (2x at the top, 1x at the rear) 100%. This may produce more noise but for cooling aspect, look if it makes a difference (it should).

To cool your HDD, things get complicated since your HDD sits outside of the airflow path of front intake fans. There are, however, dedicated HDD cooling kits out there but outside of big NAS/RAID setups, they are rarely used,
newegg: https://www.newegg.com/Hard-Drive-Cooling/SubCategory/ID-577?PageSize=96

E.g Scythe SCIT-1000,
newegg: https://www.newegg.com/Product/Product.aspx?Item=9SIA9ZH3T86558

Mounted on HDD,
image:

Btw, it is possible for you to mount your rad at the top without MoBo clearance issues but in order to do that, you need to install fans outside of the case in pull setup. It doesn't look pretty but it get's the job done,
image:

Oh, one last question. I wonder, why you have 1kW PSU in there? I'm interested in your reasoning behind selecting 1kW unit.
 

terragady

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Thanks for nice answer and info. Yes I thought about installing rad on top with fans on outside, does not look pretty and I would have to remove the top mesh which will allow that some small particles, dust and dirt to go inside when PC is OFF. That would be my last solution. I have tried to run my exhaust at 90% and it helps, it is loud though. I have set a curve for PCH so they sits around 50% when idle and low load and goes to 100% when PCH temp is rising, will test it but looks like good plan.

About the 1kW PSU I just had one, I bought 3 PCs for parts, one came with rm1000i and it was giving weird noises so I exchange it because it still had a warranty and I got a new unit so thought that I will keep it. The others were rm1000 without i, old version and rm650X which would be also fine and is little shorter but I guess it does not harm to have 1000W, maybe one day I can use it for something else. For me there was no price difference between either of them so why not :)
 

Aeacus

Illustrious
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Reason why i asked about PSU is that way overpowered PSU (1kW) would have worse efficiency than smaller capacity (e.g 650W) unit. Since PSUs are most efficient when load on them is between 50% and 80% of max wattage output.

GTX 1080 Ti is 250W GPU and provided that your CPU isn't Core i9 or Xeon, the rest of system would consume about 200W, making 450W total at max load (CPU and GPU 100%). On idle your PC consumes about 200W or so. 1kW unit would operate between 20% and 45% load while 650W unit would operate between 30% and 69% load.

Due to that reason, any modern gaming PC build with single GPU setup doesn't need more powerful PSU than 650W. For low- and medium-end GPUs (e.g GTX 1060), 500W range PSU would be more than enough.
If the price is same between 650W unit and 1kW unit then yes, it makes little difference which one to get. But most of the times, 1kW unit can cost up to twice of a 650W unit and here, it does matter, especially if budget is tight.
 

terragady

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yes I know about the PSUs. iCue showing efficiency of about 87% minimum so I think this is still fine. Energy in Norway is cheap :) most of it coming from renewable sources so not a biggie ;)
 

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