What temperature reading does the CPU-fan use for control.

U6b36ef · Aug 23, 2014

What temp is being used to guide the CPU fan? It's probably best to set out the picture of what I am doing, and then what I am observing.

My PC case has 5V, 7V, and 12V settings for the case fans. In all monitoring, I am using the 5V settings. This runs case fans at the slowest, but still does a good job of cooling. The purpose of using minimal case cooling is specific. I want to know my CPU cooler will protect my CPU in any situation, under load like gaming. E.g. If I forget to switch up case fans. (Neither do I want to use any motherboard Asus BIOS fan tuning to make a more aggressive fan profile. I want the cooler to be independently sufficient.)

The CPU is an i5-4690, and is specced to T-case 72'C and Intel say add on 5'C for CPU core temp = 77'C. (http://www.tomshardware.co.uk/forum/id-1800828/intel-temperature-guide.html) I think that is max temp, but may be the CPU throttle of the boost clock.

Initially I was running a Freezer 7 Pro = max temps 66'C, (CPUID-Hardware Monitor). This wasn't brilliant but it was within spec. However I was only running games like Crysis 2 which were pushing the CPU to just 65% load. In all possibility a 100% load might exceed the CPU max temp.

I then bought a better cooler, the Noctua NF-U12S which gave = max temps 55'C, (CPUID-Hardware Monitor). Again this was under about 65% load. I think this cooler will probably protect the CPU under any situation, case fans low, CPU load full, etc.

Later after installing Asus AI Suite with Asus Probe II, I saw a vastly different CPU temp. Asus monitoring = 37'C max. [Core Temp and Speccy agreed with CPUID-HM.] [Speedfan agreed with Asus software.]

This is the issue and it's implications. What temperature is the CPU-fan being controlled by. I suspect the Asus software monitoring at 37'C. I read online, and a forum general opinion is Asus software uses the CPU socket temp, not CPU core temp. The Noctua fan runs from 300RPM, to 1500RPM, yet under load the CPU-fan is maxing at 384RPM. It must think the CPU is still very cool.

Effectively, I think the way the CPU temp is monitored for fan control, may have cost me another CPU cooler. I think if the real core temp was used, the Freezer 7 Pro would have spun faster and been doing a better job.

Yingda Wang · Aug 23, 2014

Guide the cpu fan? cpu temps ofc

nukemaster · Aug 23, 2014

Most boards have a certain discrepancy. I have personally seen anything from 5-15c difference. The average I see is about 5-7 different.

If this is a board sensor or another sensor is up for debate. Some have stated that Intel has another analog sensor in the cpu, but not right in the cores them selves. This can make sense when you think of the variation that even one core to the next can have even with them being all in the same chip and VERY close to one another.

Either way, the Asus software(including the bios) is designed to only adjust speeds when it is NEEDED. So things would adjust as the cpu got closer to its thermal limits. This fan speed change is delayed even more when you use the silent profile.

You should be able to leave it that way.

You can also try prime95 to stress the cpu and see how the fan reacts. Please note prime95 is more load then any games on the market and will make things run hot.

U6b36ef · Aug 23, 2014

I think I will try Prime 95. I have been using Hot CPU Pro Lite Edition. It maxes all four cores but still only uses about 65% TDP of the CPU, and reaches temps akin to gaming.

With the CPU only going up to about 55'C CPUID Hardware Monitor, with CPU at 65% load, I feel safe. I think the Noctua cooler will control temps even under max TDP and core load.

Today I switched the Asus fan control from 'standard' setting to 'turbo' mode, which is more aggressive. It keeps temps to 50'C CPUID Hardware Monitor: 35'C Speedfan. This is with case fans in min speed settings. When I turn up case fans, it's cooler.

I know I said above that I wanted not to use a more aggressive fan control. That was purely because I outright wanted the CPU to be safe without any additional tuning. That's just in case I ever forgot the additional tuning or case fan speeds. I think I have accomplished it. I think that replies your post Yinda Wan.

I will leave the Asus software guiding the fan for now. I think the same setting is available in the BIOS, which doesn't require the Asus software running. Even better. I will never forget it, even after a re-install.

Thankyou very much for pointing out Prime 95. I have seen it mentioned before, but never tried it. Good point that it may just be discrepancy readings that makes the wide variation in temps. My conclusion is that it is the Asus temp that is guiding the CPU-fan as it barely left minimum RPM. If it's not the correct core temperature, then the CPU wasn't being cooled quite enough.

nukemaster · Aug 23, 2014

I would not worry, the board has been designed to keep a stock cpu cooled. Now because the stock coolers tend to run hotter(even at stock speeds), the trigger point for the fan speed ramp may be higher. You can customize it in the bios if you want.

You could tell it to max at lets say 45-50c(bios temp) and them if things got too hot it would max out to prevent damage.

I have never had a board fail to control the fan enough resulting in a system overheating. A failed fan on the other hand will cause issues(the cpu will throttle to prevent damage and if it still gets too hot, the system will shut off.).

This is my current fan profile. The fan stays at min until 40c bios cpu temps(about 50ish core). At this point it slowly ramps until the cpu reaches 60c bios(70+ core). Now because my temps do not get this hot, it has never actually went full speed. If needed, it will.

U6b36ef · Aug 30, 2014

Hey sorry it took me a week to reply. I didn't get a notice in my email that you had added another post.

I have run Prime 95 and it does run my CPU harder than Hot CPU Pro does. I have been able to gauge that the Noctua cooler will keep the CPU protected under any conditions:

Temps only reach low 60'C with full wattage load and 100% CPU usage (case fans minimum).
Temps reach 55'C if I turn up the case fans to medium.
Temps reach only 50'C if I initiate a more aggressive fan profile.
These temps are all from CPUID Hardware Monitor, so Speedfan reads much lower.

I think I will set the BIOS to control the fan speed as you have shown. Otherwise I have to run Asus Probe software to control the CPU fan, which loads up on boot-up.

(The bizzare thing I noticed was that CPU fan speed seems to be controlled by the higher CPU temp of Hardware Monitor. I expected it to be run by the Asus software temp. I suspect it is being operated by the Asus BIOS temp reading, not the Asus Probe software temp. Of course I can't see the BIOS temp reading when I am in OS.)

nukemaster · Aug 30, 2014

The bios reads temperatures from a sensor chip.

Programs like HW monitor can see all the sensors connected to the chip. You may also notice that in some cases you will see a temperature that makes no sense at all. This is generally because no sensor is attached. It is kind of like having and amp for 5.1 sound and using 2.1. you HAVE 6 channels, but only 3 are in use.

The motherboard and possibly VRM temperatures may also trigger fan speed increases.

Hwmonitor actually shows CPUTIN as 60c all the time on my system(never changes. well unless you count the running multiple monitoring software causing false readings for a split second now and then). My actual temperature is TMPIN3

At lease your tests show you should be good under any load.

Remember video card heat may add a bit to the system too.

U6b36ef · Sep 1, 2014

Mmm, I have lots of temps that make no sense, like HW monitor shows my motherboard temp as 115'C. Asus probe see it about 27'C. I have a real mish-mash of bizzare temperatures though from Speedfan and HW monitor.

I think my worst case one was with my old Acer PC, which had an extrmeme incorrect temp reading. I think it was hotter than nuclear fission in the heart of the sun. I think I took a screen pic of it. I'm sure it was in the billions of degrees C.

Anyway yes you're right. CPU temp good under any load with minimal cooling. Sublime temps with case fans and turbo mode in the Asus software.

Speedyclip · Mar 5, 2015

Many programs, including ASUS's fan expert use the cpu socket sensor for fan control. That allows for cooling without a working cpu and more consistent readings. Unfortunately that doesn't show or use the actual cpu temperature.

You should use intel XTU to discover the actual cpu temps.

Typically all fans:chassis, cpu, etc plugged into motherboard are governed by the cpu socket temperature. 3rd party coolers may have the option to use their own sensor or the cpu on chip sensor and have a better chance at controlling cpu from heating up excessively. Normally all you can do is get close, i.e. 10 to 20 degree difference with lots of thermal lagging too. Good Luck

U6b36ef · Mar 5, 2015

Speedyclip :

Many programs, including ASUS's fan expert use the cpu socket sensor for fan control. That allows for cooling without a working cpu and more consistent readings. Unfortunately that doesn't show or use the actual cpu temperature.

You should use intel XTU to discover the actual cpu temps.

Typically all fans:chassis, cpu, etc plugged into motherboard are governed by the cpu socket temperature. 3rd party coolers may have the option to use their own sensor or the cpu on chip sensor and have a better chance at controlling cpu from heating up excessively. Normally all you can do is get close, i.e. 10 to 20 degree difference with lots of thermal lagging too. Good Luck

I never heard of XTU. Cool. (No pun intended.)
Thanks.

Speedyclip · Mar 9, 2015

U6b36ef :

Speedyclip :

I never heard of XTU. Cool. (No pun intended.)
Thanks.

Speedyclip · Mar 9, 2015

XTU is Intel's Extreme Tuning Utility for CPU overclocking. Available at http://www.intel.com/content/www/us/en/motherboards/desktop-motherboards/desktop-boards-software-extreme-tuning-utility.html

Cheers

U6b36ef · Mar 9, 2015

Helpful that you replied, because I downloaded XTU and completely forgot about it. Anyway I installed it now. Here's a run-down of idle temps.

XTU - 29'C
CPUID HWMonitor - 29'C
Core Temp agrees with CPUID but gives individual temps, and not a package temp.
Speedfan - 26'C
Asus Utility suite - 26'C

(Load temps show the apps remain in sync. I.E. Speedfan and Asus Utility monitor the same.)

The XTU could be handy for me later if I ever need to overclock. I have the Intel i5-4690, and a motherboard which does not have CPU overclocking. However I don't know if I will ever get to overclocking it. I think by the time it starts to get slow across many games I will buy a new mb/CPU. However you never know, there may be just one game comes along that is CPU intensive.

My old PC, an Acer T671 had an E6700 and that was slow across almost all new game titles. I had a GTX650 Ti Boost installed so it wasn't the GPU, (graphics setting permitting). None of the Crysis games would run fluently. The only games that would run were e.g. the Fear series, the Dead Space series. Serious Sam3 BFE would run but needed the CPU settings reduced from ultra to high. Even then it lagged a little occasionally.

Basically though I used Clockgen to overclock with, as the board had no overclocking options. (I doubt Clockgen would work with my 4690 so I'd need XTU for that.) However the short story of it all is this. Even with the overclock on it made little improvement in games that were struggling for fraps because of the CPU. Therefor I think a new gen CPU is much the better option.

Speedyclip · Mar 9, 2015

So HWMonitor and XTU cpu temp are showing the actual cpu on chip temperature sensor. I guided you to XTU to know exactly what temperature sensor is what. Speedfan and Asus utility are using a sensor mounted on motherboard mounted under the CPU chip. The on chip sensor is the one that counts for actual temperature and shouldn't be much higher then 70C ever. That means the motherboard sensor you're using for regulating the cpu temp should be set somewhat lower; perhaps 55C to 60C as a maximum. The cpu socket sensor is usually going show a lower temp then the actual cpu. Hope this helps you.

U6b36ef · Mar 9, 2015

I saw load 56'C with XTU, but only 36 with Speedfan. That's way too much discrimination. I was surprised it didn't go higher considering I only had case fans on lowest setting. However it was only 19'C in my room. Noctua NF-U12S CPU cooler.

nukemaster · Mar 10, 2015

56 is still very good for a core temperature.

I have not used speedfan in a while, but it used to be ok for both core and bios temperatures.

The onboard temperature sensors on most cpus is designed with cpu protection(throttle to prevent damage) in mind and are not always 100% accurate at lower temperatures anyway.

Karadjgne · Mar 10, 2015

The Asus fan xpert is by far the best fan control software of any other than SpeedFan, and is real easy to set up. It does have 1 discrepancy though and that is cpu temp as read by Asus probe. Mine would get to 40°C and stay there even under p95 small fft with a liquid cooler. I have no clue where this temp came from, even package temps were higher. However, the fan temp settings in fan xpert do not register by that temp, but by core temp. I've run coretemp, hw monitor, real temp, speccy and they all agree that the cpu fan ramps up according to fan profile settings at the temp specified. Not a problem anywhere.

Wise man in here somewhere once posted 'it's software, take it with more than one grain of salt, its probably wrong' and to that I agree. Asus probe is buggy, but fan xpert isn't. Hope that helps.

U6b36ef · Mar 10, 2015

I was left wondering about this since I posted load results. Just now I figured that probably, Intel XTU is right. It's their chips and I guess they would want people getting the right readings.

Speedyclip · Mar 10, 2015

U6b36ef :

Looks like you're cool now.(pun intended). I run 37C at idle and 68C at load. These are cpu chip temps. I use Asus xpert fan control from on motherboard sensor and use whatever settings to make these temperatures happen. I use only Noctua fans: 3 -140mm and 2 -120mm and have adjusted all them for lowest noise while keeping my cool. I use a Corsair 550D case for reduced noise.

U6b36ef · Mar 10, 2015

nukemaster :

Yeah I am comfortable with it. I chose the Noctua cooler to make sure my CPU temps could be completely safe. Meaning if I left the case fans on low: and that is the set up which makes 56'C. If I turn up case fans it's better and I do sometimes in gaming. I remember you once said use the motherboard headers for case fans. I never got round to it. Either way, at the moment, my motherboard and CPU are good.

I do run it with a CPU turbo 'fan setting', but even on standard it holds my CPU in a safe zone. With safety in mind it's a good point that the CPU would throttle down if it got too warm.

The Freezer 7 Pro I had before was holding at about 66'C which was a little toasty, at min case fans.

Karadjgne :

I think that sounds right. When I applied Asus Fan Expert and let it analyse my fans it actually raised by CPU temps. I un-installed it and settings and re-installed the Asus Suite. I don't let it analyse fans anymore and run Fan Expert on default Turbo setting.

Speedyclip :

Hey like I just mentioned when using Asus Fan Expert and let it ananlyse fans, I get hotter temps. Maybe revert back to having a pre-set Fan Expert setting like I do and see what you get. Got to be worth a look, if you didn't already.

I am looking for some more case fans I think. Plus my CPU fan is a little noisy. It whirrs every time it hits about 850rpm and above (range up to 1500rpm). That means even opening or closing apps gets whirr. OK but not good! I think it's faulty. I hope it will run as a case fan in its quiet range. I hope to get a replacement for the CPU and put that on the cooler. Noctua actually offered me a free replacement. I must get back to them on that. It's been a while I hope they still will. The fan is silent most of the time. Only Crysis 3 made it whirr quite a bit and just putting case fan on medium cured it. Adding another case fan or two will only help to keep temps even lower anyway. Probably not increase noise either. My PC is mostly silent. Just a sort of quiet electronic hiss that's just quiet fan noise, and slight HDD noise.

I think I will have to pick your posting to Intel XTU as the best solution. That's because XTU re-assures me the most. I do not know for concrete sure that it uses an on-chip sensor. I think like you say it uses socket temp and that's definitely close enough. I was happy to see it agreeing with HW Monitor and core temp. I was dreading it being out of sync even further with the apps I already looked at.

I usually feel bad choosing a best solution though. As you can see nukemaster has applied vast effort to his thread. (Nuke's suggestion Prime95 which I had never heard of was invaluable for testing temps. I have used Hot CPU Pro Lite Edition before. However Nuke still put up info for everyone to see.)

Speedyclip · Mar 10, 2015

U6b36ef :

nukemaster :

Yeah I am comfortable with it. I chose the Noctua cooler to make sure my CPU temps could be completely safe. Meaning if I left the case fans on low: and that is the set up which makes 56'C. If I turn up case fans it's better and I do sometimes in gaming. I remember you once said use the motherboard headers for case fans. I never got round to it. Either way, at the moment, my motherboard and CPU are good.

I do run it with a CPU turbo 'fan setting', but even on standard it holds my CPU in a safe zone. With safety in mind it's a good point that the CPU would throttle down if it got too warm.

The Freezer 7 Pro I had before was holding at about 66'C which was a little toasty, at min case fans.

Karadjgne :

I think that sounds right. When I applied Asus Fan Expert and let it analyse my fans it actually raised by CPU temps. I un-installed it and settings and re-installed the Asus Suite. I don't let it analyse fans anymore and run Fan Expert on default Turbo setting.

Speedyclip :

Hey like I just mentioned when using Asus Fan Expert and let it ananlyse fans, I get hotter temps. Maybe revert back to having a pre-set Fan Expert setting like I do and see what you get. Got to be worth a look, if you didn't already.

I am looking for some more case fans I think. Plus my CPU fan is a little noisy. It whirrs every time it hits about 850rpm and above (range up to 1500rpm). That means even opening or closing apps gets whirr. OK but not good! I think it's faulty. I hope it will run as a case fan in its quiet range. I hope to get a replacement for the CPU and put that on the cooler. Noctua actually offered me a free replacement. I must get back to them on that. It's been a while I hope they still will. The fan is silent most of the time. Only Crysis 3 made it whirr quite a bit and just putting case fan on medium cured it. Adding another case fan or two will only help to keep temps even lower anyway. Probably not increase noise either. My PC is mostly silent. Just a sort of quiet electronic hiss that's just quiet fan noise, and slight HDD noise.

I think I will have to pick your posting to Intel XTU as the best solution. That's because XTU re-assures me the most. I do not know for concrete sure that it uses an on-chip sensor. I think like you say it uses socket temp and that's definitely close enough. I was happy to see it agreeing with HW Monitor and core temp. I was dreading it being out of sync even further with the apps I already looked at.

I usually feel bad choosing a best solution though. As you can see nukemaster has applied vast effort to his thread. (Nuke's suggestion Prime95 which I had never heard of was invaluable for testing temps. I have used Hot CPU Pro Lite Edition before. However Nuke still put up info for everyone to see.)

I'm glad I could help. I like to suggest another cpu stress tester too, RealTemp GT. It uses Prime95 for load and will actually use the chip sensor for evaluation of coolness!

Karadjgne · Mar 10, 2015

For Intel cpu's I like RealTemp and speccy, both are within a degree of each other, which is good enough for me. speccy will also give a considerable amount of other info, and its usually the stuff you have to have a degree in Win7/8 IT to find, which is cool

U6b36ef · Apr 21, 2015

nukemaster :

I think I worked out why you thought 56'C was such a good temp. I was using Prime 95 on default setting. There is a more aggressive setting which doesn't stress the RAM, and I think other parts.

When I used the more aggressive setting I was going into 60+'C, and I think I hit 65'C with fans on minimum. middle fan setting only pulled off 1'C. I think my Freezer 7 Pro would have struggled with this setting, and might have throttled. Or at worst closed down. However I can't be sure.

In reality though there isn't an application I use that will max the CPU for a good time. Crysis 3 only pulls max 65% CPU.

Anyway I have the option to increase fan speed. Plus I have the option to add fans to the chassis. I only have three in place, with two at the CPU drawing out air. I have one on the front of the case. I should comfortably add a couple more fans. One on the base, blowing up through the chassis, and maybe one feeding the CPU with air drawn in.

Thank you for your extensive contribution. Anyway we know now Intel XTU must be the one for monitoring Intel chips. That it concurred with CPUID Hardware Monitor was assuring. We can use HM for watching everything when needed. The only measurement it doesn't cover is video-RAM usage really.

Karadjgne · Apr 21, 2015

When running prime95, its best to use v26.6.Versions later than that use an aggressive avx approach which leads to funky hot temps that are totally unrealistic. For stress use small fft settings as it has the most consistent stress vrs other settings which raise and lower cpu usage.

As far as Asus fan Xpert goes, analyzing the fans is fine, the program tries to balance performance with quietness, keeping low, acceptable temps, not necessarily the lowest possible temps. What you do is set to turbo, which is coolest but fastest, then adjust the graph according to what temp range you want. I had one set rather narrow, 20%fan under 35, 35-40 was green, 30% fan, 40-55 yellow 60% fan then 55+ was 100% vrs stock 70 at 100%.
This meant I was running dead silent at anything normal like surfing or Photoshop etc, but when gaming the fans went upto 60% (About 900rpm which on an nf-f12 is still almost a whisper) and if I stress tested fans went to 100 before the test barely got started. Worked extremely well that way.

Also to consider, when it comes to the cpu all temps under @70°C are identical. Makes exactly no difference at all if the cpu is 56° or 36°, most large server banks run 50-70° 24hrs a day, 365 days a year and not even blink at those temps.

nukemaster · Apr 22, 2015

You have many options for fan control, but even 65 is not bad.

Some users want the lowest temperatures and fill all fan slots(just make sure they are somewhat balanced to keep the air moving). Other users will go with the minimum required to keep things within spec.

I get into the low 60's in games on my system and do not worry about it at all. The cpu will be long obsolete before it fails.

What temperature reading does the CPU-fan use for control.

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