Overclocked i7 8700K temps constantly fluctuate between 62c and 81c

[chorltonwheelie]

Hi TH hivemind,
I have OC'd my 8700k to 5GHz on my Maximus X Hero using an Arctic Liquid Freezer 240.
When stress testing at 100% load using Prime95 or Intel's Extreme Tuning Utility the temperature cycles between 62c and 81c.
As I could hear the cooler fans rising and falling I thought whacking them on full speed would result in a steady core temp....nope. The temps still fluctuate in the same manner.

Q: Though I'm comfortable with 81c in a stress test (it goes nowhere near that while gaming) I'd like to see a steady temperature that won't be expanding and contracting the die every few seconds, how can I achieve this?

If anyone has any ideas and can point me in the right direction without too much hand holding I'd be extremely grateful.

 

[CompuTronix]

chorltonwheelie June,

On behalf of Tom's Moderator Team, welcome aboard!

Fluctuations are normal and expected, especially when running fluctuating workloads. Prime95 "Blend" and Intel ETU are both fluctuating workloads. However, Prime95 Small FFT's is a steady workload, which doesn't fluctuate. It's also important that you do not run any versions later than 26.6.

The 8700K has a feature called "Speed Shift" which causes frequent fluctuations, particularly at idle. If you still have fluctuations during P95 Small FFT's, then it's likely you may have background startups, processes and services running which are causing thermal fluctuations.

Read our Guide; Sections 4, 11, 12 & 13: Intel Temperature Guide - http://www.tomshardware.com/forum/id-1800828/intel-temperature-guide.html

Once again, welcome aboard!

CT

 

[chorltonwheelie]

What a lovely welcome!

The 8700k speed shift seems to work differently to my trusty i5 3750k's speed step (only just replaced it as i had it screaming along at 4.7Ghz on air for years).
The fluctuations are a little more pronounced but nothing to frighten the horses I think.
I just needed a little re-assurance I hadn't done anything terribly wrong.

Thanks CT.