Very unstable wattage

[Rnn15]

An hour ago, I was browsing on the internet, not doing anything intensive. Suddenly the cpu fans (2x120mm fans, closed loop liquid cooling) started working at full capacity, then stopped a few seconds later. They did that again, but this time did not stop. I opened HWmonitor, and noticed the cpu temperatures were in the 90 degree C, when they usually don't go over 65C under heavy load.

I restart my computer, update it, run a full virus scan. Nothing is detected, and the cpu fans are not acting weird anymore. Even the cpu temps are back to normal values.

However I noticed on HWmonitor that the power is very unstable. Under the CPU's "powers" section, both the "package" and "IA cores" keep moving. "package" keeps moving between 28W and 32W, with a one time spike to 71W. For the "IA cores", it's moving between 12W and 18W, also with a one time spike to 54W. Even the CPU's voltages are unstable, moving between 0.8V and 1.2V. In contrast, the GPU's voltage is constant, at 0.887V.

Should I be worried?

Thanks for the help

 

[GhislainG]

This is normal; as soon as a task runs, CPU utilization increases, etc. Check if the system is stable at full load and make sure the cooler works properly.

 

[Rnn15]

This is normal; as soon as a task runs, CPU utilization increases, etc. Check if the system is stable at full load and make sure the cooler works properly.

After further research, I found out that this is indeed normal.

However, the same thing happened again today. CPU temps spiked and fans started working at full capacity for no reason. This is the second time it happens. And every time, it happened after a cold boot, around 15-25min after turning the computer on. A restart brings the temperatures directly back to normal.

Could it be a sensor problem?

 

[GhislainG]

It possibly is a bad sensor, but we have no clue what system you have. If it's an Intel system, then download and install Intel XTU to monitor it. If AMD, then download and install AMD Overdrive. To have the fans run at full speed the CPU has to be working hard, the heat sink is not making good contact or there's a hardware issue.

 

[Rnn15]

It possibly is a bad sensor, but we have no clue what system you have. If it's an Intel system, then download and install Intel XTU to monitor it. If AMD, then download and install AMD Overdrive. To have the fans run at full speed the CPU has to be working hard, the heat sink is not making good contact or there's a hardware issue.

The relevant parts of my system

Motherboard: Intel DX79SR
CPU: Intel i7-3930k Sandy Bridge-E
Heatsink: Coolermaster Nepton 240M

 

[GhislainG]

Are you sure your cooler is working properly? It should keep your CPU much cooler than that, particularly when it isn't that busy. Let Intel XTU run in the background and check how busy and hot the CPU is when the cooler fans start running at full speed.

 

[Rnn15]

Are you sure your cooler is working properly? It should keep your CPU much cooler than that, particularly when it isn't that busy. Let Intel XTU run in the background and check how busy and hot the CPU is when the cooler fans start running at full speed.

Idle CPU temp: 35 degree Celsius

I also ran a CPU and memory stress test using Intel XTU. The CPU temps during the stress test didn't go higher than 60 degrees.

 

[GhislainG]

XTU doesn't stress anything; the fan on my CPU doesn't even become audible. For a real stress test use Prime95 and monitor temperatures while running it.

 

[Rnn15]

I stress-tested my CPU using prime 95 for 5 hours. There were 0 errors reported. The temperature wouldn't go above 60 degree Celsius.

What do you think?

 

[GhislainG]

I think that's outstanding!

 

[Rnn15]

Then what do you think the problem is?

 

[GhislainG]

If according to XTU it doesn't throttle while running Prime95, then you have a bad sensor or a cooler issue; it may sometimes run too slow for an unknown reason.

 

[Rnn15]

I re-installed the cooler, just in case it wasn't properly installed the first time (which I doubt). I'll see if the problem continues.

 

[Rnn15]

If according to XTU it doesn't throttle while running Prime95, then you have a bad sensor or a cooler issue; it may sometimes run too slow for an unknown reason.

Hey,

So I turned on my PC this morning, and it happened again. Fans were working at full capacity, and Intel XPU was showing me very high CPU temps (90 degrees), but I noticed that no heat was coming out of the case.
I re-installed the cooler two days ago or so and made sure everything was in place.

It does seem like a sensor problem, doesn't it?

 

[GhislainG]

Either a bad sensor or a cooler that isn't working properly. You can't feel heat unless it's been happening for several minutes.