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PC tempetature sensor and override


DTMark

Question

Since I'm still without my office PC thanks to the lockdown, I've bought a reconditioned one here in Italy. I didn't want to spend a fortune, just to buy something good enough for development, and so this is a Dell Optiplex small form PC.

It was fine for about two hours then the fan started making so much noise I actually thought my partner was hoovering the apartment.

I've been looking into this and installed some software that enables monitoring of the temperature sensors. It looks to me like the ambient temperature sensor is faulty.

The normal fan rate is 1600 which is silent. What's happening from boot (it doesn't go for two hours now, it's immediate) is that it's spinning up to 4500 which makes a hell of a noise.

I should really send it back for a replacement, but I did get as far as installing the OS and copying content onto it and I really don't want to have do all that again.

The software can override the BIOS settings and keep an eye on things, and I've configured it to up the fan rate when the processor temperature hits 40 which is doesn't reach very often (it is at that temperature now as the processor is very busy with something I've set it doing). This works nicely.

Can the ambient sensor be replaced or is it a case of replacing the motherboard? Does it matter if I set the software to ignore that sensor and instead just work from the processor temperature sensors?

Is my conclusion about the fault likely to be right and is the PC likely to survive with my override, at least for, say, six months bearing in mind it gets hotter in Italy than the UK, or must I return it now and get a replacement?

 

pc-temp.thumb.jpg.e9a3ebd5704b1124bc38f96371095197.jpg

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7 answers to this question

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This is interesting as I've just replaced a SFF 745 with another similar machine. The original one was starting to show signs of a known problem which, in my limited understanding, was something to do with the graphics chip beginning to fail. Anyway, it was always a noisy machine with the fan often spinning up. So far the new one is a completely different animal. It does have twice as much RAM, but I noticed as I was installing the SSD that this one has the additional cooling fan beneath the hard drive, as per @The XYY Man's pictures, that the other one never had. It still lasted seven years, which was more than I could expect for my eighty quid. This one was £45!  

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41 minutes ago, eight said:

This is interesting as I've just replaced a SFF 745 with another similar machine. The original one was starting to show signs of a known problem which, in my limited understanding, was something to do with the graphics chip beginning to fail. Anyway, it was always a noisy machine with the fan often spinning up. So far the new one is a completely different animal. It does have twice as much RAM, but I noticed as I was installing the SSD that this one has the additional cooling fan beneath the hard drive, as per @The XYY Man's pictures, that the other one never had. It still lasted seven years, which was more than I could expect for my eighty quid. This one was £45!  

Two chips in a PC that have the consistently highest power density are the CPU and GFX chip, hence both of them often needing additional cooling - either static finned heatsinks or fan assisted ones or reliant on internal airflow.  So GFX chip failure would not be surprising, keep the internals cleaned out, if you can use compressed ai or vac  to keep all the fins clear in heatsinks etc. 

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20 minutes ago, onlyme said:

Two chips in a PC that have the consistently highest power density are the CPU and GFX chip, hence both of them often needing additional cooling - either static finned heatsinks or fan assisted ones or reliant on internal airflow.  So GFX chip failure would not be surprising, keep the internals cleaned out, if you can use compressed ai or vac  to keep all the fins clear in heatsinks etc. 

It's this problem.

https://www.dell.com/community/Laptops-General-Read-Only/Solid-color-screen-crash/td-p/3613937

That is regarding a Dell laptop but I had the same problem on a desktop. There are quite a few similar links describing the same problem with no definitive resolution. Wasn't worth investigating when I could get a whole replacement machine for the price of basically any spares/investigation. I expect this one will go the same way, eventually.

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Think you have that right - ambient sensor will be on the board and will mainly affect the setting of the case fan hence affect mainly the motherboard / disk drive temps.  Set the main motherboard fan speed to something that is acceptable noise wise but higher than baseline to err on the side of caution Your processor temps look pretty cool and these are the really important ones. Most PC fans / vents are clogged with cruise within a few years so cool nowhere near as efficiently as they are designed to - keep on top of that and keep the internals clean and would be surprised if you had any problems in the summer.

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23 hours ago, The XYY Man said:

I have a small form OptiPlex 790 as my back-up PC. Not sure if you have the same model, but the advice I give here will apply to most Dell models.

Dells are designed very well when it comes to pulling them to bits, so don't be scared to have a go - you don't need to be that technical a person. If you get the user manual for your model, it has full instructions and lots of diagrams.

Hope this helps,

 

XYY

Thanks - yes, it is very similar - a Dell Optiplex 7010, looks basically the same. I'll give all that a go - thanks!

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Equally, if your software solution has solved the noise problem and your CPU temps are in the 40s I'd say you have absolutely nothing to worry about. When I started overclocking in the early 2000s you'd find that instability set in above maybe 60 degree core temps, but nowadays 80C seems to be a perfectly acceptable operating temperature, and temps into the 90s only cause the chip to start to throttle, rather than die. So you should be fine now and still fine even if ambient temps ride 10-15 degrees. Keep the inside of the PC free of dust obv, but I'm sure you knew that already...

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