[SOLVED] CPU ramping temperature at start-up and then suddenly fine

[Fardale99]

Hey.

Posted before but I kind of let it died due to being busy but here we go again.

I have an unusual problem with cpu temperature on startup.

If I go to Bios:
The cpu will slowly ramp up (1oC at a time) up to 70/71oC.
For about 1-3 minutes, the cpu temperature will sit at this temperature.
After this period, the cpu temperature will VERY RAPIDLY drop to around 23-27oC (depending on room temp) and will stay this way even when I boot to windows and I never see it go above 45oC under heavy loads (and this is rare. mostly sits at 35oC when gaming).

If I let it go straight to windows:
It will idle randomly at anywhere between 45-80oC and will never drop until I restart it. (at least as far as I know as I usually shut it down asap in case it rockets to the 80oC level which is just ridiculous)
No unusual activity or high usage in task manager. Usually 2-7% utilization idle which is the same as when it is overheating and when it isn't (after going through the bios method).

about 1/20 times there will be no problem on startup and will boot straight to windows with it's typical <29oC idle. The fans work appropriately according to the temperature.

So recently I've been letting it run in BIOs to run through the process where it ramps up until it decides to chill out and stop whatever is making it go crazy before booting windows and carry on with my day. Once it has 'chilled out', it can stay on all day without a blip. I can game, watch vids, do assignments. Let it run for 24 hours once just to see. No problems.

Bios has been updated and windows clean reinstalled despite my hate of doing both. Nothing changed.

It is a fairly old setup now but it's still strange how it runs completely fine despite this startup blip. It's been fine like this for a while now but of course i'm worried this will ruin the cpu in the long run and I'd like to keep it for as long as possible as it will fit all my needs for a while. It's like it takes a few mins just to realise it's overheating then suddenly goes "whoops", flips a switch and it's fine until I want to turn it off and start it up again later/next day.


Anyway. the setup.

It's the coffeelake build from overlcockers.
Just copy pasted the build from order cart. If you need more info please let me know. Up to date with all drivers. Everything is cleaned regularly and once this problem is over, cooling of the cpu works like a dream as it has since it was purchased.
The problem first occurred after both a huge windows update (one particular dodgy one I don't remember which. version that messed up bluetooth?) and i gave fans a clean straight after it finished so had the case open etc so don't know if i knocked something or if windows messed something up in bios magically somehow. Probably because I was messing in case but doesn't explain how it magically fixes itself after a few mins in bios. but...bios so... windows update seems unlikely too? +did clean reinstall ... so really don't know lol.


Kolink KL-850M 850W 80 Plus Bronze Modular Power Supply
Asetek 240mm 670LT Thick Radiator
Phanteks Eclipse P350X Glass Digital RGB Midi Tower Case - Black (one fan at the back, two in front from radiator)
Gigabyte Z390 UD Intel Z390 (Socket 1151) DDR4 ATX Motherboard
Gigabyte 256GB M.2 PCIe x2 NVMe SSDSolid State Drive
EK Water Blocks EK-Cable Y-Splitter 2-Fan PWM (10cm)
LGA11Asetek Premium Retention Kit Intel 5X
Microsoft Windows 10 Home Advanced - Systems
Team Group Vulcan T-Force 16GB (2x8GB) DDR4 PC4-24000C16 3000MHz Dual Channel Kit
Build Promo Intel Core i7-9700K 3.6GHz (Coffee Lake) Socket LGA1151 Processor
System Build Fan - Noiseblocker BlackSilent Pro Fan PLPS - 120mm PWM (SI) EXNO-001
Zotac GeForce RTX 2070 Mini 8192MB GDDR6 PCI-Express Graphics Card

 

[kerberos_20]

so issue might be from your water loop, thats the only explanation which makes sense

 

[Fardale99]

so issue might be from your water loop, thats the only explanation which makes sense

Huh... I'll slap myself for being stupid if that's the answer.
The weird intermittent behaviour switched my head away from cooling problems as it is clear the fans are working (and somehow forgot what i look at everyday through the glass side is a water loop) and didn't feel like it should be getting warmer like that just from being started up. But if the heat is just sitting in that one spot in the loop before being taken to the fans it makes tons of sense (if I'm understanding it right)

Will troubleshoot bit later/ tomorrow ...

Thanks for the help.

 

[DRagor]

But if the heat is just sitting in that one spot in the loop before being taken to the fans it makes tons of sense

That would only be possible if pump would not work at the start, only to turn on later. Even if your loop was built in such way that there is a pocket of fluid that sits in place instead of moving around that would not explain why it changes after some time. Right?

 

[Fardale99]

That would only be possible if pump would not work at the start, only to turn on later. Even if your loop was built in such way that there is a pocket of fluid that sits in place instead of moving around that would not explain why it changes after some time. Right?

Honestly no idea. but if it's not pumping straight away and coming on later maybe there's a delay for some reason or the pump is just initially struggling to get going? Considering everything else I've tried and considering it's only the cpu being affected it makes sense. Still open to other suggestions while I look into it. Been driving me nuts for ages.

 

[Fardale99]

Update:

Okay. Cautiously optimistic here.

I realised that at some point while messing in bios I may have hit them back to default (was a prebuilt machine). This may have caused the fan settings to adjust to normal rather than being setup for water block.
So I checked to see which wires were connected to which fan ports on the motherboard and made it so the pump had only 2 stages (60% for anything under 35oC and 100% for over). I read it's fine to keep it at 100% for blocks but pump let out a little bit of noise so I set it like this which is also apparently fine.

Edit: it was set to react to "system one" (whatever sensor that is) temp too so it didn't react to cpu getting hot. I'm guessing it didn't get enough juice until after the rest of the pc warmed up which might explain the delay before it kicked in. Maybe.

I also 'wiggled' the cable/pipes... technical genius I know.

When I turned on the computer this morning with these settings, the cpu temp started climbing again but this time it stopped around 32oC and dropped pretty quickly. May just be having a good day but If this continues for another couple restarts I'll consider this one solved (it doesn't last as long if i just shutdown/restart after it has been running for a while so will have to wait until I turn if off for a long period). Though not sure why it still has an initial climb. Maybe pump just decided it was old one day and needed a bit of extra juice or maybe it was just because i defaulted settings. Dunno. Will see if its fixed before i investigate further.

Thanks for the help so far.
(CPU heating up... connected to water block... forgot that's what it was so been stumped for about a year... sigh)

 

[DRagor]

made it so the pump had only 2 stages (60% for anything under 35oC and 100% for over).

Not sure if running pump at variable speed is good idea. I would rather set it to one speed all time, probably as high as you can while still silent enough for your taste.

it was set to react to "system one"

That alone could cause your problem. System one is probably sensor that measures motherboard temp, and those go up much much slower then CPU can. By the time mobo reached enough temp to actually run your pump/fans fast enough your CPU was already cooking itself. Good that you caught that.

 

[Fardale99]

r: 22364
Not sure if running pump at variable speed is good idea. I would rather set it to one speed all time, probably as high as you can while still silent enough for your taste.

Ah okay, thanks. I'll do that then. When I started up again just now after getting home it hit 35oC again before kicking in again so I'll make sure it's just 'ON' from now on and leave it alone.

r: 22364
That alone could cause your problem. System one is probably sensor that measures motherboard temp, and those go up much much slower then CPU can. By the time mobo reached enough temp to actually run your pump/fans fast enough your CPU was already cooking itself. Good that you caught that.

Starting to suspect this is right on the money. Just set them to default and they've been set on a fan curve and monitoring random things. Can't believe I forgot it had water block. Thought I cheaped out on when I bought the system lol. Somehow convinced myself it was "just a heat sink (magically) connected to front fans." Ah well. Alls well that ends well.

Thanks for solution @kerberos_20 and thanks for the feedback and advice @DRagor. gonna mark this as solved and pray that it stays that way.
Cheers