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I've had this system that I've wrestled with it's CPU fan speed noise for a while now. And after building a new comp that is near silent it's put this system's issue back in sharp relief.



What will happen is that the CPU fan speed will slowly, and seemingly for no good reason, creep up until it's pegged at the fan's max speed of about 4.1k. Now the odd thing is is will actually go back down again if for example the system sits idle overnight. But as a rule the fan speed as you can see, the above SS was taken of the HWM which started at around 9am and it's now just a little before 1pm, will want to creep up.

Mainboard Vendor ECS
Mainboard Model 915PL-A2 (0x1DB - 0x8FBC26)
Specification Intel(R) Celeron(R) D CPU 3.06GHz
Core Speed 3220.2 MHz (23.0 x 140.0 MHz)

The CPU itself is slightly OCed but even were I to have it at stock speed the same issue apply. So, I've got a few questions:

While CPUTIN is pretty self explanatory, I assume it's a thermal diode sitting under the socket, what/where do SYSTIN and VTIN monitor?

And of course why is this happening and what can I do about it? I'd prefer not to have to hardwire the CPU fan to 5 or 7V but with how annoying this thing has become it's starting to look like a good option. (This computer is now in my office where I often watch TV so to have it whining while it's doing nothing is really a bummer.)

Welp, as you can see just as promised the CPU fan speed is now pegged. And yet the temp values show no reason for it.

Grrr...

Not really sure what the problem is for you. But my CPU fan dose this to. I have always figured it was to keep the cpu at its right temp. Just about every computer I have had. Has done this.More so if I am running a lot of programs at one time. I would think if you put thermal compound on the cpu when you installed you should be fine. If not I am sure someone here can help you.

Storm90 wrote:Not really sure what the problem is for you. But my CPU fan dose this to. I have always figured it was to keep the cpu at its right temp. Just about every computer I have had. Has done this.More so if I am running a lot of programs at one time. I would think if you put thermal compound on the cpu when you installed you should be fine. If not I am sure someone here can help you.

Thanks for the reply Storm. The thing is this is not a CPU cooling issue. The CPU currently, and has been, doing just fine. Rather somewhere...something is making the motherboards wacky for lack of a better way of putting it. (And as far as it goes the thermal compound between the CPU and it's heat-sink is fine.)

There are precious few controls in this mobo's BIOS for the CPU's cooling fan. Furthermore I've tried using Speedfan to crank down the fan's speed and no dice. So I'm at the point of just hardwiring it to 5 or 7v. However before I do that I want to make sure I've exhausted all my options.

YoshiMon wrote:Thanks for the reply Storm. The thing is this is not a CPU cooling issue. The CPU currently, and has been, doing just fine. Rather somewhere...something is making the motherboards wacky for lack of a better way of putting it. (And as far as it goes the thermal compound between the CPU and it's heat-sink is fine.)

There are precious few controls in this mobo's BIOS for the CPU's cooling fan. Furthermore I've tried using Speedfan to crank down the fan's speed and no dice. So I'm at the point of just hardwiring it to 5 or 7v. However before I do that I want to make sure I've exhausted all my options.

Do you have your cpu overclocked? Other then that I never run across such a issue.

Well it could be missreading the temps, or mis labeling them. Are you sure its the fan on the cpu that is speeding up? Fan0 should be for the cpu.

there might be options in the BIOS to control the fan speeds, look in there.

Storm90 wrote:Do you have your cpu overclocked? Other then that I never run across such a issue.

Only slightly. From my OP:

Mainboard Vendor ECS
Mainboard Model 915PL-A2 (0x1DB - 0x8FBC26)
Specification Intel(R) Celeron(R) D CPU 3.06GHz
Core Speed 3220.2 MHz (23.0 x 140.0 MHz)

The CPU itself is slightly OCed but even were I to have it at stock speed the same issue[s] apply.

there might be options in the BIOS to control the fan speeds, look in there.

Well, as I said there are precious few controls in this mobo's BIOS for the CPU's cooling fan. In fact there is exactly one control explicitly relating to the CPU fan's speed. Here it is from the manual, engrish included at no extra charge.

CPU TM Function (TM2)
This item displays CPU’s temperature and enhances you to set a safe temperature for CPU.

Turning it on or off makes no difference.

Well it could be missreading the temps, or mis labeling them. Are you sure its the fan on the cpu that is speeding up? Fan0 should be for the cpu.

My gut is telling me that this is the rub. That there are two factors going on here. One is that the BIOS which is controlling the fan's speed is getting a false reading maybe. Or that the algorithm that is controlling the fan's speed was written poorly. Or both.

This morn I checked it and the fan had throttled down to 3k. And just a bit ago it had gone back down to 2k. So there is something at work there but with the information I can get from the system it's hard to tell what it's trying to do.

My only guess at this point is that it might have a thermal diode on one of the bridges and one of those is getting, likely the northbridge, too hot during the day. I've got an extra fan that I might try plugging in and sticking on top of that chip I suppose.

Welcome to SpeedGuide Yoshi!

The fan could be bad or going bad...
I have never had much faith in the mobo correctly monitoring the fan speed or the actual temp...

Thanks Ken. I suppose that too is indeed a possibility. However given the fact that it seems to be acting on some form of logic of it's own it seems that the hardware is ok.

In fact the more I think about it the more I am warming up to the idea, heh heh, of it being the northbridge that is heating up. And then for whatever reason the BIOS thinks that by cranking up my CPU fan it will solve that problem. I suppose given the placement it was actually designed like that but gah.

Oh and I forgot in my last post but yeah the fan's labels are indeed correct. Depending on the system chips the CPU sometimes might be listed 1st but not always.

Try putting a fan on the NB... See if that levels out the cpu fan speed...

To be honest, the only fan that I hook up to the mobo is the cpu fan. IMO, no need to be sending that juice through the mobo and I have the control over those fans... (case, NB, SB, etc...)

Well there is the new fan. Time to give the system a workout and see how it does!

Good luck! Let us know...

PS Folding is a great way to run your system to the max (using all your unused resources) and it may help to find cures/preventions for some of our worst diseases. See/click my sig if you are interested...

Le sigh. Went and played Mass Effect for about 45m. That game pushes this modest system to it's limit and then some so rightfully so the CPU fan slowly but surely picked up speed.

However now after I've stopped playing and just have let the comp sit here and do basically nothing it's not cranked the fan speed back down. I'm afraid that whatever the algorithm and or sensor it's using to set that fan's speed is just fubar. Oh well.

Well after a bit more searching to no avail I just got done rewiring the system.



I did my normal stress test of playing some Mass Effect and you can see the CPU peaked at 44°C. The chip is rated at a max of 67°C so for now I'm happy with the results. Come summer time I'll have to make sure it's doing OK and if needed bump it up from 5V to 7V.

Finally in the pic is maybe a clue as to what was going on. Notice that even thou that both the SYSTIN and CPUTIN are higher the VTIN is lower. I've always had a sneaking suspicion that the VTIN, whatever it really is, was a prime cause of this whole mess. Silly thing.

Check application of heat sink on the CPU....excess thermal grease sitting around...possible a blotch on the thermal sensor?

I have seen motherboard BIOS upgrades fix faulty thermal control systems.

Well it is a LGA775 socket so while there is an actual possibility of some TIC having gotten in the hole in that socket, or elsewhere, given the nature of what I've done with this computer it's highly unlikely. One of the 1st things I did when starting this process was take the whole thing apart, save for the CPU/heatsink assembly since it's that stupid pushpin setup, and clean it. That would leave the only possibility of there being any sort of thermal diode being 'blotched' in that small hole in the LGA socket itself. And that sensor has never been the issue, rather...

The !#$%&!@ VTIN sensor which I think is the issue. Given that it's value has gone DOWN now that I've manually reved down the CPU fan leads me to believe that it's a calculated value rather than an actual sensor. And I wore out Google looking to see what the damn thing was and while I never found out exactly everything that I did find pointed to it indeed being a calculated value based on the systems other sensors. However I've got a strong feeling that they flipped a 1/x to x/1 as it were in the programming for it.

To that end I did indeed upgrade the mobo's BIOS at some point in this process. However I did not hold out much hope as it was only like a 3 month upgrade and the revision notes did not say anything about my issue. And I sure as hell don't want to dig around in a disassembler to see if the BIOS code is indeed the problem. I'm happy now with this setup and the system is very stable as well. Gonna just call it a win.