Insufficient cooling for CPU

[kenzig]

Hi,

I had recently posted for an advice on weather I should get a liquid cooler for my i7 4790K, since I am getting high temperature readings while rendering (about 100 C).

I brought the Coolermaster Seidon 120v Plus yesterday and there is barely any difference in the temperatures now. Just getting an average of 2-3 degree difference!

Am I doing something wrong?

I am in the middle of a project that needs loads of rendering, so I need some advice guys.

Thanks in advance!

 

[noidea_77]

Do you see temp related throttling while rendering?

 

[JackNaylorPE]

I don't quite understand why water is automatically assumed to do a better job of cooling than air. After all, water is just a transfer medium. It works in custom loops as you are replacing the heat sink with large radiators, and pumps capable of moving enough water thru them. In the end, cooling is actually accomplished by moving air across a radiator instead of across a heat sink. So both use air / metal heat transfer .... but to get it there one uses metal to metal contact whereas the other uses metal to water to metal.

CPC type water cooling units have never been shown to outperform comparably priced air coolers.... and when they manage to get close, it's simply because, they have replaced quiet 1200 rpm fans with fans which run much faster and noisier.

http://www.hitechlegion.com/reviews/cooling/liquid/40870-swiftech-h220-x-open-loop-240mm-cpu-cooler-review?showall=&start=2

Here we see the cheaper Noctua NH-D15 w/ (2) 1500 rpm fans beating the Corsair H100i w/ (2) 2700 rpm fans by 2C while H100i needs to be 12 times as loud to stay that close.

 

[kenzig]

While rendering, when a frame starts the temperature shoots from 50 C to 95 C in 20 seconds!

@JackNaylorPE, water should at least do a better job than stock i7 4790? I think..

 

[noidea_77]

While rendering, when a frame starts the temperature shoots from 50 C to 95 C in 20 seconds!

@JackNaylorPE, water should at least do a better job than stock i7 4790? I think..

Of cause it heats fast, because modern render application tend to use all cores of your cpu to get the maximum performance out of it. But do you see throttling ? Is the CPU still running at full speed / max frequency when rendering ? If yes, there is no need to worry.

 

[kenzig]

[/quotemsg]

 

[noidea_77]

[/quotemsg]
And as far as I can see, all your answers are in the picture! All four cores are running at full speed and the max temp is directly related to the smart fan settings. The CPU fan hits max rpm at 100°C. Change that to 95C and you will see the difference.

 

[kenzig]

Manually set all fans to Full RPM! No success! 🙁

 

[capt_taco]

If you're running the CPU at 100% (which is what it will do in things like video rendering) while using the stock cooler, then of course you will heat it up. But you don't need water cooling. As explained exquisitely above - water cooling is air cooling. You are simply moving the heat transfer location to a different place.

I suppose in the immediate short term, water cooling could soak up more heat because of the capacity of the liquid to store heat, but while running at 100% for a sustained period, over the course of 45 seconds or so, once the water circulates back around, there is not much fundamental difference. It all depends on how much heat the radiator and fan can blow away.

A big air cooler, or even a decent medium-tier one, will solve your problem for a fraction of the price, and a mere sliver of the trouble and complication, of water cooling.

 

[JackNaylorPE]

While rendering, when a frame starts the temperature shoots from 50 C to 95 C in 20 seconds!

@JackNaylorPE, water should at least do a better job than stock i7 4790? I think..

Metal is a better conductor than water. It's basically a weakest link in the chain thing.

Scenario 1 - Metal heat plate, conducts heat to large heat sink which is cooled by blowing air thru it.

Scenario 2 - Metal heat plate conducts heat to water which moves it to a radiator which is cooled by air.

In both cases, it's the air cooling of the heat sink / radiator which is the weakest link.... having water as a middle step doesn't change anything.

Put two 140mm fans @ 1500 rpm on a heat sink and two 140mm fans @ 1500 rpm on a radiator and performance will generally be comparable. With CLCs however, sacrifices in pump quality and radiator size, necessary to meet a price point usually mean that usually mean that the air cooler will outperform the CLC.

In order to get water to outperform air in an all-in-one unit, you need to move to a unit that is basically a custom loop pre-assembled at the factory. These will have copper instead of aluminum rads and much more powerful pumps. But you'll notice that in order to beat the D15 air cooler by that 5C, it needs to have higher rpm fans which are twice as loud.

As for the curves, I have fans set to 100% at about 75C.

Since this is a "work project" with workdays full of rendering, I'd use nothing less than the H240-X