Case airflow in water cooled PC

LuckyBenski

LuckyBenski

LuckyBenski

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Hey all, so I've built my first custom loop (hardline, 360mm and 120mm rads, i5-4690k and GTX 1070).

System temperatures are great - generally below 50 degrees C, maxing out at 53 under stress test. And very quiet. But I've noticed internal temperatures seem really high. Reading for PCH and that are fine, but the heatsink on the PCH is burning up. Right on the line between pain, and leaving me actually burned.

I'm using an Alphacool GPX Nexxxos block which is a hybrid block, so I know some of the heat is carried throughout that block rather than into the loop. The backplate of the GPU block is almost as hot. I'm just kind of surprised!

Right now I have two intake fans blowing from the top down, and the radiators exhausting (360mm at front, 120mm top rear). It seems like no air is reaching the centre of the case. The intake fans are fixed speed (slow), but the radiators are all on a curve based on temperature.

Any suggestions for improvements? I'm tempted to put SP fans on a PWM curve in the intake slots too...
 
You have your fans the wrong way around, from what you describe, sounds like the air coming in from the top is being exhausted straight out the back by the rear 120 fan, plus exhausting on the 3 front fans, therefor negative pressure inside the case.

Just remember, hot air rises, and live by that.

So turn the 3 at the front around so they are bring the air into the case, and the 2 at the top and 1 at the back as exhaust, the front 3 you'll want running slightly faster than top / rear 3, say 1000 rpm for front ones and 850 for the exhaust fans = positive pressure in the case.
 
See I've been surprised how often "hot air rises" is a misnomer in PC cases. My quietest and coolest machine to date has two intakes on top and one exhaust in back. It is a cube case with horizontal motherboard though, so kind of a different beast to typical ATX cases.

I've considered reversing the front fans, it wouldn't be too difficult, just didn't want to dump all that heat into the case. Surely it won't help the internal temp situation? I don't need my CPU/GPU any cooler, just want the case itself to get more air.

1000rpm would be pretty unacceptable noise-wise for me, except at absolute full load!
 
Ahh OK, I'm using corsair LL120 fans, they are completely silent at 1000rpm so just working from that, but my new lian li case suffers from the same problems you describe, but there's no front intake or exhaust, it's at the side, so the only way I could work it at all was to use the lower right side fans as exhaust and the top 2 as intake, nothing at the rear, the 3 exhaust are at 800 rpm and top 2 are running 1000rpm
 
Hadn't heard of those fans. They look like ML120s, I'm quite interested in checking out the newer Corsair fans. Currently using SP120s on the radiators. Good but noisy-ish...
 
They are very good fans, I'm impressed, but a lot of wiring, check out the HD version of the thermaltake riing fans too, less wiring, and great radiator fans too.
 
My last case I had 360 rad as front intake and 240 rad as top exhaust for both CPU and GPU block. Last summer I put a thermometer on the top as it felt quite toasty, if I remember right it didn't go above 32c with a room temp of about 25c. I don't think that is a lot of heat to put into the system. As far as I'm aware CPU doesn't really produce a lot of heat to worry about and the card runs a lot cooler than air cooled so less heat is created as a by product.
 
If you have a search you will find many threads about the GPU backplates being ‘hot as the sun’. This means they are doing their job passively cooling, Ive personally tested a fan directly at it rendering it cold to the touch... zero difference in the GPU temperature or performance, conclusion: it’s fine don’t touch it.

I don’t think you have an issue as you say the temperature of the component under the heat sink is fine.
 
Smffy said:
If you have a search you will find many threads about the GPU backplates being ‘hot as the sun’. This means they are doing their job passively cooling, Ive personally tested a fan directly at it rendering it cold to the touch... zero difference in the GPU temperature or performance, conclusion: it’s fine don’t touch it.

I don’t think you have an issue as you say the temperature of the component under the heat sink is fine.
Click to expand...
True, I know that even the motherboard itself is doing fine. Is it fairly normal for a watercooled system to have poor case temperatures?
 
LuckyBenski said:
True, I know that even the motherboard itself is doing fine. Is it fairly normal for a watercooled system to have poor case temperatures?
Click to expand...

Just a flow issue, I would personally take in cool air at the front and exhaust top and/or back. My setup is in through the bottom and front then out the top.

That said if the pc is working well and hardware temps are ok then there isn’t really an issue so to speak :)
 
After many different attempts at setting up my fans to find the best temps I ended up with rear 140mm intake & exhaust 120mm front, 140mm top.
Seems to work athough I don't know why.
 
Robzere31 said:
After many different attempts at setting up my fans to find the best temps I ended up with rear 140mm intake & exhaust 120mm front, 140mm top.
Seems to work athough I don't know why.
Click to expand...
This is what's great about it though - every situation is different and experimentation is good! I'm obsessed with quietness so usually rig up my case with all the fans before building, and test using batteries and 6V power supplies. If I can't get it quiet like that, I rearrange until it's better.
 
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