Shutdown instability when overclocking

xyphic · 6 Jan 2016 at 09:21

Hi all,

I have a month-old Skylake i5-6600K build that's been running well overclocked to 4.1 GHz (using the EasyTune software that came with the motherboard). Temperatures were all good, and I'd read that an overclock to 4.4 GHz should be pretty straightforward.

So I went ahead and set the multipliers to 44 and set Vcore to 1.36. Prime95 ran for 3 hours before I stopped for the evening with no errors and decided to shut down. Only I couldn't shut down... the PC went through the normal power-off process, turning off all the fans and LEDs, then between 5 and 10 seconds after going completely silent, it turned back on. This process was completely repeatable.

I tried various things to try to rectify the fault (e.g. making sure no peripherals were configured to wake on activity) but I simply couldn't get the shutdown to stick. The only thing that would cure it was to return the overclock back to the 4.1 GHz setting.

This seems like a very odd failure mode, so wondered if anyone had seen or heard of anything similar. FWIW, the motherboard is the Gigabyte Z170X Gaming 7 with F3 BIOS. Also worth noting that droop seems to be fairly high as Vcore reports anywhere from 1.28 to 1.33 while under load.

Cheers,
xyphic

Loxa · 6 Jan 2016 at 17:25

xyphic said:
Hi all,

I have a month-old Skylake i5-6600K build that's been running well overclocked to 4.1 GHz (using the EasyTune software that came with the motherboard). Temperatures were all good, and I'd read that an overclock to 4.4 GHz should be pretty straightforward.

So I went ahead and set the multipliers to 44 and set Vcore to 1.36. Prime95 ran for 3 hours before I stopped for the evening with no errors and decided to shut down. Only I couldn't shut down... the PC went through the normal power-off process, turning off all the fans and LEDs, then between 5 and 10 seconds after going completely silent, it turned back on. This process was completely repeatable.

I tried various things to try to rectify the fault (e.g. making sure no peripherals were configured to wake on activity) but I simply couldn't get the shutdown to stick. The only thing that would cure it was to return the overclock back to the 4.1 GHz setting.

This seems like a very odd failure mode, so wondered if anyone had seen or heard of anything similar. FWIW, the motherboard is the Gigabyte Z170X Gaming 7 with F3 BIOS. Also worth noting that droop seems to be fairly high as Vcore reports anywhere from 1.28 to 1.33 while under load.

Cheers,
xyphic

Does it shutdown with no overclock?

xyphic · 6 Jan 2016 at 21:48

Loxa said:
Does it shutdown with no overclock?

Yes, it only fails to shut down when the overclock is significant.

Loxa · 6 Jan 2016 at 22:10

xyphic said:
Yes, it only fails to shut down when the overclock is significant.

First thing that comes to mind is unstable OC, maybe up the voltage a little bit. Running a memtest also could be something worth while to try.

xyphic · 6 Jan 2016 at 22:14

Loxa said:
First thing that comes to mind is unstable OC, maybe up the voltage a little bit. Running a memtest also could be something worth while to try.

It definitely seems to be related to the overclock. I found it funny that it was stable running Prime 95 for three hours, but falls over after shutdown!