Strange CPU temp jumps

[phluxer]

A month ago i puchased a EK Phoenix LQ system with a 280 radiator to cool my CPU and GPU and at the beginning everything looks fine and i got ~40°C for both the CPU and GPU at idle.

The last few days i noticed that the CPU temp sometimes suddenly rises to ~65°C at idle without any change at CPU/GPU load and without me doing anything special on my system.

My first guess was that i had an air bubble in the loop that sometimes got stuck in the CPU block but shaking the case to get the air moving seems not to do anything and i also don't see any weird temp changes like this on my GPU.

 

The temperature change on the CPU happens nearly instantly and can last about a minute up to 10-15 minutes as far as i could see.

When the temps get back to normal it sometimes happens instantly too, and sometimes it goes half the way down to ~55°C for 1-2 minutes and then back to normal.

 

I'm new to liquid cooling and this seems very strange behavior to me. Does anyone has any suggestions what can cause this?

 

P.S.:

I'm also afraid to open the loop and topoff the liquid to get rid of any air, because i guess that could contaminate the loop and i have chosen the EK Phoenix because its maintenance free and i want to keep it that way.

If anyone can tell me if i'm wrong about that it would be very helpfull as well.

[knightslugger]

it's possible it's a malfunctioning thermal sensor in the CPU or socket. Is your BIOS up to date?

[Skiiwee29]

Usually when you get spikes like that, its from background processes like windows updates etc kicking off and checking things. If you're afraid of air bubbles, take and gently rock the system back and forth and side to side to jostle it a bit and break them free to let them reach the reservoir. I have a full custom look and its about 2 weeks old under its current iteration and fill and I still do it to break the bubbles up and out. Just got some good ones out yesterday. It can take a few days, or even weeks to fully bleed the system of air bubbles. 

[phluxer]

Yes the BIOS is up to date 

2 minutes ago, knightslugger said:

it's possible it's a malfunctioning thermal sensor in the CPU or socket. Is your BIOS up to date?

Yes the BIOS is up to date and i never saw anything like this with my aircooler. 

 

2 minutes ago, Skiiwee29 said:

Usually when you get spikes like that, its from background processes like windows updates etc kicking off and checking things. If you're afraid of air bubbles, take and gently rock the system back and forth and side to side to jostle it a bit and break them free to let them reach the reservoir. I have a full custom look and its about 2 weeks old under its current iteration and fill and I still do it to break the bubbles up and out. Just got some good ones out yesterday. It can take a few days, or even weeks to fully bleed the system of air bubbles. 

 

As i said in my post, the CPU load does not change while the temperature spikes, and i have higher temperatures on full load if i start a stresstest whithin this spiking periodes. So its definetly less cooled while that happens. 

Also shaking the system doesn't do anything to it. The reservoir on this system is very small and i guess if there is too much air maybe its not big enough to hold all of it.

But on the other hand i can't head any air moving through the system as i would when the bubble moves away from the CPU right?

[Skiiwee29]

Just now, phluxer said:

Yes the BIOS is up to date 

Yes the BIOS is up to date and i never saw anything like this with my aircooler. 

 

 

As i said in my post, the CPU load does not change while the temperature spikes, and i have higher temperatures on full load if i start a stresstest whithin this spiking periodes. So its definetly less cooled while that happens. 

Also shaking the system doesn't do anything to it. The reservoir on this system is very small and i guess if there is too much air maybe its not big enough to hold all of it.

But on the other hand i can't head any air moving through the system as i would when the bubble moves away from the CPU right?

I will also cycle my pump speed and/or system to help purge it too. I use Argus Monitor to control my pumps speed and can manually change it from 0 RPM to 100% with a slider so ill do this at times as well as power cycling the system. Try running the pump at 100% for a few days/weeks and shaking it around gently. The common place the air bubbles get trapped is in the radiators so you may have to shake it for a while to get them flowing outward. 

[phluxer]

So you guys think its an air bubble issue?

I don't really know how the EK Phoenix pump behaves and if it changes speed at all. Sadly i can't controll the pump direcly or readout the speed.

I've plugged it into the CPU header and it shows up just like a normal fan.

So i'll try to run it at 100% fan speed for a while and hopefully the pump will ramp up as well.

[phluxer]

Update: 

I think i have found the problem! It seems to be a bug in MSI afterburner which i used to observe my temperatures.

If i look at HWMotior, Aida64 or even SpeedFan normal temps around 40°C are shown while afterburner says the CPU temps are ~70°C.

I have no idea where afterburner gets this temperature from but i can't find this temperature readouts anywhere in those other programs.

So i think its some kind of ghost readout because i trust HWMonitor or Aida way more.

 

Thanks for your help guys, it looks like it was my fault to not check multiple sources to confirm my temperature readouts.