Running semi passive cooling

lovelyhead · 11 Jul 2016 at 23:24

I have a NZXT H440 case and have just purchased a NZXT Grid+ V2 digital fan speed controller. My goal is to get my computer as quiet as possible.

I am currently using the stock case fans with a Cryorig H5 Universal CPU cooler.

My CPU is a 2500K overclocked to 4Ghz and my GPU is an MSI 290X.

I thought I would do a little experiment to see how hot my CPU and GPU would run at idle with all fans turned off (except the 290X as the fans always spin).

I was expecting the CPU to overheat quite quickly what with the combined heat from the GPU and CPU being dumped into the case, but was surprised to see that the temperature stabilized at ~67 degrees C. Ambient temperature in the room is 23 degrees C.

Would you be comfortable with your CPU running this warm most of the time?

BluD · 11 Jul 2016 at 23:38

If your cpu is at 67 idle then your heat sink must be pretty hot like 50 degrees maybe, wouldnt your fans then have to go really fast every time you add a little load to the CPU? Normally you would have to heat up the heat sync first so you have a bit of a buffer allowing your fans to ramp up slowely.

Its only a guess cause i always water cool so i dunno how fast things heat up with air.

lovelyhead · 11 Jul 2016 at 23:55

BluD said:
If your cpu is at 67 idle then your heat sink must be pretty hot like 50 degrees maybe, wouldnt your fans then have to go really fast every time you add a little load to the CPU? Normally you would have to heat up the heat sync first so you have a bit of a buffer allowing your fans to ramp up slowely.

Its only a guess cause i always water cool so i dunno how fast things heat up with air.

I am still experimenting, but I have set the NZXT Grid+ to switch the CPU cooler on once the CPU reaches 70 degrees. It spins the fan at 35%. It then incrementally increases the speed as the CPU gets hotter.

I ran prime95 for a while there and it was leveling off at roughly 80 degrees.

DarkBahamut · 12 Jul 2016 at 00:06

Is that 44C delta temp at idle?

I don't think 67C is an issue per se, but if you do have a 44C delta at idle then that leaves a lot to improve on for sure. You can almost certainly do better without increasing noise at all.

lovelyhead · 12 Jul 2016 at 00:09

DarkBahamut said:
Is that 44C delta temp at idle?

I don't think 67C is an issue per se, but if you do have a 44C delta at idle then that leaves a lot to improve on for sure. You can almost certainly do better without increasing noise at all.

Hi, Sorry I am unsure what you mean by delta temp?

DarkBahamut · 12 Jul 2016 at 00:14

The difference between the ambient temp and the achieved temp. 23C -> 67C = 44C delta. It means if your room got to 30C your CPU would run at 74C, assuming no change to cooling being applied

But yes, that 67C temp you got was at idle?

lovelyhead · 12 Jul 2016 at 00:25

DarkBahamut said:
The difference between the ambient temp and the achieved temp. 23C -> 67C = 44C delta. It means if your room got to 30C your CPU would run at 74C, assuming no change to cooling being applied

But yes, that 67C temp you got was at idle?

Yes 67C at idle. Just browsing and watching videos etc.

Doing more testing, I have linked the case fans to the GPU's temperature. They will only start spinning when the GPU reaches 60C. My 290X stablises at 85C and the CPU at 55C running the heaven bench. The CPU fan doesn't even come on as it isn't reaching the required 70C.

Very impressed with the Grid so far.

DarkBahamut · 12 Jul 2016 at 00:59

I think you should maybe run the CPU/case fans all the time personally. With the GPU fans always spinning your system will never be silent. I had an MSI GTX 780 with the twin forzr IV cooler and while it is 'quiet' it's a very long way from being actually silent at idle. It's easily louder than some slow spinning CPU and case fans, which means you can drop your CPU temps down nicely without actually adding any extra noise to your system.

I spent about a year tweaking my setup and without removing my mechanical hard drive I simply cannot get any better than this from a noise perspective.

Room ambient noise: 21dB (A very very quiet bedroom/office)
Room ambient temps: 21C

CPU cooling: Noctua NH-D14 with stock fans. 550RPM (120mm) 480RPM (140mm) idle / 850RPM (both) gaming load
Case: 4 * Scythe S Flex 120mm @ 550RPM idle / 850RPM gaming load
GPU: MSI GTX 970 with Twin Forzr V fans stopped at idle / ~1000RPM gaming load
PSU: Corsair AX750 fans stopped at idle / ~500RPM gaming load

Idle performance:
Noise levels: 22dB (+1dB over ambient)
i7 2700k @ 4.4GHz temps: 32C (11C delta)
GTX 970 @ 1.45GHz temps: 40C (19C delta - passive cooling)

Gaming performance:
Noise levels: 27dB (+6dB over ambient)
i7 2700k @ 4.4GHz temps: 45C (24C delta)
GTX 970 @ 1.45GHz temps: 62C (41C delta)

You can really get some great noise levels without having to stop any fans as long as you can just run them slow enough. Even a little airflow really brings temps down. If you have any source of noise in your PC at all, be it a GPU or even a mechanical hard drive then you can almost certainly get away with ~500RPM on your case and CPU fans without impact noise as long as they are decent fans.

I could stop my own fans, but with a 7200RPM HDD, even with it being very very quiet at idle, it's not quite silent, so no gains from stopping the fans as the overall noise level doesn't decrease. That said, at a mere 1dB of noise increase the PC is almost impossible to hear anyway. I'd love to go totally silent, but replacing 3TB's worth of storage with SSDs is just too much cost for a 1dB drop

lovelyhead · 12 Jul 2016 at 01:31

DarkBahamut said:
I think you should maybe run the CPU/case fans all the time personally. With the GPU fans always spinning your system will never be silent. I had an MSI GTX 780 with the twin forzr IV cooler and while it is 'quiet' it's a very long way from being actually silent at idle. It's easily louder than some slow spinning CPU and case fans, which means you can drop your CPU temps down nicely without actually adding any extra noise to your system.

I spent about a year tweaking my setup and without removing my mechanical hard drive I simply cannot get any better than this from a noise perspective.

Room ambient noise: 21dB (A very very quiet bedroom/office)
Room ambient temps: 21C

CPU cooling: Noctua NH-D14 with stock fans. 550RPM (120mm) 480RPM (140mm) idle / 850RPM (both) gaming load
Case: 4 * Scythe S Flex 120mm @ 550RPM idle / 850RPM gaming load
GPU: MSI GTX 970 with Twin Forzr V fans stopped at idle / ~1000RPM gaming load
PSU: Corsair AX750 fans stopped at idle / ~500RPM gaming load

Idle performance:
Noise levels: 22dB (+1dB over ambient)
i7 2700k @ 4.4GHz temps: 32C (11C delta)
GTX 970 @ 1.45GHz temps: 40C (19C delta - passive cooling)

Gaming performance:
Noise levels: 27dB (+6dB over ambient)
i7 2700k @ 4.4GHz temps: 45C (24C delta)
GTX 970 @ 1.45GHz temps: 62C (41C delta)

You can really get some great noise levels without having to stop any fans as long as you can just run them slow enough. Even a little airflow really brings temps down. If you have any source of noise in your PC at all, be it a GPU or even a mechanical hard drive then you can almost certainly get away with ~500RPM on your case and CPU fans without impact noise as long as they are decent fans.

I could stop my own fans, but with a 7200RPM HDD, even with it being very very quiet at idle, it's not quite silent, so no gains from stopping the fans as the overall noise level doesn't decrease. That said, at a mere 1dB of noise increase the PC is almost impossible to hear anyway. I'd love to go totally silent, but replacing 3TB's worth of storage with SSDs is just too much cost for a 1dB drop

Thanks for the advice. I have no mechanical hard drives so the only noise my PC makes is coming from the fans. My 290X always spins it's fans but I am looking to sell that and get a new gpu which stops the fans at idle.

I think I really need to look at replacing the stock NZXT fans with some noctuas.

Telecaster · 12 Jul 2016 at 19:53

Don't worry too much about fan brands, there isn't a magic bullet to be had down the road of just buying more expensive fans.

The enemy of the silent PC is not which brand of fan you use but how fast it spins.

As the owner of a few totally passive PC builds I can say it's doable.

Firstly, is speedstep enabled along with all the relative CPU power saving features? As 67c at idle seems very high for a CPU with a decent heatsink on it.

Very slow running fans can be deadly silent whilst offering just enough air flow to keep things under check at idle, with good fan curves set for load then you will be sorted.

lovelyhead · 12 Jul 2016 at 23:50

Telecaster said:
Don't worry too much about fan brands, there isn't a magic bullet to be had down the road of just buying more expensive fans.

The enemy of the silent PC is not which brand of fan you use but how fast it spins.

As the owner of a few totally passive PC builds I can say it's doable.

Firstly, is speedstep enabled along with all the relative CPU power saving features? As 67c at idle seems very high for a CPU with a decent heatsink on it.

Very slow running fans can be deadly silent whilst offering just enough air flow to keep things under check at idle, with good fan curves set for load then you will be sorted.

Thank you for the advice. I will hang fire on the Noctuas!

Doing more tweaking tonight and I am finding some very surprising results. I turned the top fan at the front of the case off and the GPU temperature dropped over 15 degrees C. This was at the expense of the CPU temp increasing 5 degrees C. As I am running a 290X, that was a drop from 95C down to 80C whereas the CPU only increased to 60C. I can now reduce the fan speed on the 290X which has the noisiest fans in the system.

Going to turn off the middle front fan to see what happens!

JonSmith · 13 Jul 2016 at 15:26

A little bit of airflow goes a long way, if you have a good heatsink then most 80mm+ fans will be inaudible outside the case if ran at 5V, and will provide significantly lower temperatures than running passively.

JanxSpirit · 13 Jul 2016 at 15:41

JonSmith said:
A little bit of airflow goes a long way, if you have a good heatsink then most 80mm+ fans will be inaudible outside the case if ran at 5V, and will provide significantly lower temperatures than running passively.

^ This.

I have Arctic Cooling F8 and F12 case fans running under BIOS control in 'Silent' mode so they only ramp up when needed. The same for the 80mm fan on the CPU cooler. They're all inaudible unless the PC is stressed yet provide sufficient airflow through the case to avoid stagnant pools of warm air. They're spinning so slowly right now that I can almost read the labels on the fan hubs.

BluD · 13 Jul 2016 at 16:43

Yeah if you have a GPU that dumps its heat into the case i would keep at least one fan going just to help get some of that hot air out, that hot air will just be heating up all your other components in there. Dont forget theres other things in there with heat syncs on that should be getting cooled by your CPU fan, vrms, mosfets, ram etc. So although your CPU might not need any fans untill 70 degrees something else might be getting a little hot.

lovelyhead · 14 Jul 2016 at 16:15

Thanks for all the advice guys!

I have set a profile for the NZXT Grid+ so that at idle I have all fans turned off except the stock 140mm fan on the rear vent. This is close enough to the CPU to keep it at about 50C at idle with the fan only spinning at 450RPM.

When at load the profile turns on all of the other fans at 100% once the GPU reaches 80C (which it does very quickly what with it being a 290X).

I have decided that a silent case is near enough impossible using a 290X as it puts out way to much heat. I have been looking at 1070's that are passive up to 60C. That seems to be the way to go.

It may be of interest to other H440 case owners but through all of my testing I discovered the best layout for the stock fans that come with the case is having the 3 120mm fans as intakes on the front and the 140mm as an exhaust at the back. Having fans on the top is a waste of time as the temps only drop between 1 and 2 degrees C. I tried both intake and exhaust from the top but it isn't worth it.

It is a pity that AMD don't make cool and quiet cards as I was looking at getting a Freesync ultrawide monitor. That will need to take a backseat for a while as I will have to pay the Nvidia premium.