Skylake Fluctuating Clockspeeds

[paulsterio]

Hey Everyone, 

 

I currently have a 6700K running at stock, with a Gigabyte Z170N-WIFI, Gigabyte GTX970 G1 Gaming, 16GB Corsair Vengeance LPX DDR4 and I have the following problem when running any intensive tasks, e.g. Prime95 or IntelBurnTest (or even repeated runs of CineBench). 

 

After about a minute of use, the clockspeed (and %ge utilisation in task manager) begin to fluctuate as follows:

 

 

I've done all the regular troubleshooting procedures, I've tried it with optimised defaults and it has this problem. I've also tried it with all of the fancy power saving measures (SpeedStep, C2 - C8 states, overheating protection...etc.) disabled as well as Turbo Boost disabled. All give the same results. 

 

Clearly it's not thermal throttling as the maximum temperature reached is only 73 degrees.

 

Anybody got any ideas? If anything, I suspect that it is a motherboard issue, as I've borrowed another CPU and it presents the same issues, but I've yet to try my 6700K in another motherboard. 

 

[Coaxialgamer]

Seems normal enough to me.  Under a heavy load,  your cpu goes to its base of an x40 multiplier,  but your bclock seems to be slightly under 100mhz,  which is normal,  as it barely ever gets to a perfect 100mhz. Remember that frequency = multiplier (40x base by default)* Bclock (100 mhz on skylake) 

Thus,  you get 3.97ghz instead of 4.0ghz

[done12many2]

Spoiler

 

 

Are you running all of your tests in High Performance mode?

[paulsterio]

2 minutes ago, Coaxialgamer said:

Seems normal enough to me.  Under a heavy load,  your cpu goes to its base of an x40 multiplier,  but your bclock seems to be slightly under 100mhz,  which is normal,  as it barely ever gets to a perfect 100mhz. Remember that frequency = multiplier (40x base by default)* Bclock (100 mhz on skylake) 

Thus,  you get 3.97ghz ins of 4.0ghz

 

It drops far below 4GHz, I'm talking around 2.6GHz and sometimes even lower. As an example, my first Cinebench run will be around 880cb (which is typical for a stock 6700K), but buy the fourth or fifth consecutive run, it's down to around 680cb. 

 

For example, here, you can see it dipping:

 

 

2 minutes ago, done12many2 said:

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Are you running all of your tests in High Performance mode?

 

Yes, I am. 

[JCBiggs]

run avx2 benchmarks and see what it looks like. if its still does it,  thermal paste...

[Coaxialgamer]

In that case,  you may be power limited,  which is totally the kind of a issue a bad motherboard would cause.  

[JCBiggs]

What it should look like..   where it spike to 100% is where the avx2 cycle started.. before that is where prime95 opened and started runing automatically.  

 

mine would do this at 3.8ghz all day with the water cooling.  (i have broadwell e)   at the least, it should stay at 100% and just drop the frequency a bit to deal with heat.  I have my mother board to set to limit core temps to 66 degrees and the avx frequency offset to -4.   ( i usually run 4.2 ghz)  

anyways,.. do prime 95 and see how it looks.  thats the best way to get a real stress test imo.   it should be consistent and flat (maxed)