Loud H105 fans when rendering

Hello,

 

My first post here. I have looked at a number of posts here on fan noise but they are pretty specific to the individual setup so I thought it best just to see if someone has run into something like what I am seeing.

 

I had a computer built recently with an i7 core. I use it for work running a rendering program which is processor intensive. The stock cpu fan was all around too noisy and its worse when rendering so I had the guy who built it put it an H105 cooler with two 240 mm fans. It was still too loud so my guy set it to silent mode in the BIOS which made normal processing really quiet but rendering is intolerable. I complained again and he kind of said, it is what it, so live with it. I just cant do that as I am ready to strangle the cat every time I have to make a rendering.

 

It sounds like fan noise so I have tinkered with the fans in the BIOS but I cannot get it to have any effect. I really hope there is some kind of adjustment for the top end or I am going to have to ditch this cooler and go to something else. I am not a super tech guy but I can take direction so if there is anything to check or do I would love to hear it.

 

Thanks,

 

Alki

Well, the H105 is a non-software cooler and so fan speeds are entirely dependent on what you set in the BIOS or whatever fan controller you connect. Presumably, you CPU temps (I am assuming this is the variable set in the BIOS) are somewhat high when rendering. You can make a decision about what speed you want. The good news is your end CPU temp is not critically tied to CPU temp. You may be able to lower fan speed with a nominal difference in temperature.

 

It's hard to be more specific without details. The fans that come with the H105 are somewhat loud generally. There are quieter versions, but it would make sense to know what speed you are seeing now and what is your noise limit (in terms of RPM).

What motherboard do you have? Most modern boards will allow you to set custom curves based on temperature when you are unhappy with the standard Silent/Normal/Performance profiles. Check the motherboard manual for instructions.

wrong thread

I am finally have some time to dig into this again. Thanks for these responses. I kind of understand how the BIOS is supposed to work but the interface does not make sense to me. I wish I had known about software driven fans before I got this one.

 

First, my motherboard is the ASRock Z370M Pro4 LGA 1151 (300 Series) Intel Z370 HDMI SATA 6Gb/s USB 3.1 Micro ATX

 

Back to the BIOS. The customize has a tab that says CPU fan 1 & 2 however it displays four nodes on a graph that can be moved horizontally from 0 to 100 degrees. The vertical is power 0 to 100. I don’t understand the relationship between the scales and the nodes. If you move a node up on the temp scale what is that doing? I mean the fan is already running. There is no RPM on the graph so what does changing a node on the power scale do?

Normal processing shows CPU usage at 8% with a temp of 51c and the fans are quiet. Running my rendering program puts the CPU at 100% but the temp only rises a few degrees. I thought the fan RPM increase was tied to the CPU temp so now I am wondering if the fan is responding to power consumption not temp.

 

Thanks.

I imagine it is a classic % of maximum fan speed (Y-axis) vs Temperature (X-axis). Unfortunately, not all fans follow a true mathematical scale. A fan with 1000 rpm max may not actually run at 500 rpm when set to 50% like it should. More often the slippery slope is at the bottom and top end of the speed curve rather than the middle where you spend most of your time, but it usually requires some experimentation.

 

The "nodes" I assume are your control/data points. You have four to work with, so set the lowest where you want to the fans to be at idle, the highest at your max fan speed limit (that you can stand) and then use the middle two to make a smoother line. Perhaps someone with an ASRock board from the last generation or two can offer more pointed advice.

 

I am more concerned if you are seeing 51C CPU temps at idle. No matter your fan speed, that should be out of reach. Can you confirm that?

Here is what speedfan is showing for temps at idle. I find this confusing because it is not clear which fan is which. Adjusting the control points in the bios seems kind of arbitrary. I have no way to know how where I set the points relates to the cooling capacity. I mean I don’t want to force the fans under what is required to maintain a certain temperature and I don’t even know what temps should be.

 

Thanks for your input, but at this point I think I am going to cut my losses and get an air cooled Noctura CPU fan and be done with water cooling.

I haven't used Speedfan in ages and it was never my favorite anyway, but I think it is safe to assume the 65K rpm numbers are jibberish.

 

The radiator fans don't cool the CPU directly, but instead help dissipate heat from the cooling loop. The unknown value on the H105 and some other coolers is the coolant or liquid temperature. Ideally the fans react to the this value rather than CPU temperature, which is far too jumpy and not necessary. Your Z370 board may have a temp probe input somewhere and you could run a 10K thermistor up to measure exhaust temp from the radiator. In most case exhaust temp = coolant temp.

 

As for your current state, you just need to set down some conservative points. The coolant delta on a 8700K is pretty small. A typical CPU render is going to be 4-7C. That means the most you can reduce your CPU temps with any amount of fan speed is 4-7C and of course 100% efficiency is not possible. The stock fans on the H105 will run about 2300-2400 rpm at 100%. You don't need that speed --- ever. My suggestion is to find your speed (noise) limit, what you can stand and be in the room with it. If that is 1500 rpm, then set a dot at 60% and whatever the highest normal CPU temp you see during the render. If you want to make that the 3rd point and save the 4th for an 85-90C=100% warning spike, that's fine. Idle you can make as low as you want. 25%=40-45C. Place the second dot in between to make a gradual slope. If your motherboard has "fan delays" (hysteresis), by all means use it. Asus boards have a 12 second option that works well. You don't need the fans to react to little jumps in CPU temp. It doesn't work that way. The coolant stream is a dumping ground for the CPU waste heat. As long as you keep removing heat in a consistent manner, the CPU is not adversely affected. However, the cold plate transmits heat both ways, so whatever heat is in the coolant stream becomes the effective minimum possible CPU temp. When the coolant gets warmer, you elevate your CPU temp basis.

 

Coolant temperature is not a super sensitive variable in relation to fan speed. You won't see dramatic shifts with small changes and it is slow to move up or down. If system 1 is running the fan at 1200 rpm and identical system 2 is at 1400, they are going be more of less the same CPU temps. Maybe 1C difference at most and your room temp will have more bearing than the fans. Don't overthink this. Slow and steady works for removing the heat from the system. The difference between an air tower and a liquid cooling system is the air tower cannot hold the same amount of heat as the water set-up. The air tower must dump its heat at a faster rate (more fan speed) and of course it dumps into the case. That may or may not be critical depending on your set-up. Either way, you will still have to get comfortable with using the BIOS for fan control for both systems.