CPU BUS Speed keeps fluctuating?

[WereCat]

Hi, so I have this problem with my CPU BUS speed which I cant find solution to resolve.

System:
i7 4770k
Gigabyte Z87X-UD4H
Gigabyte 770OC WF3
Crucial Ballistix Sport 2x8GB 1600MHz CL9
Super Flower Golden Green 550W

This is what I sent to Gigabyte Support:
still waiting for reply, I am asking whenever is possible as I would like to resolve this problem ASAP.

CPU BUS speed is fluctuating and I dont know what is causing it. In BIOS when the BUS speed is set to AUTO it never reaches x100MHz but instead it keeps changing between 96-98MHz constanly and occasionaly it falls even as low as 93MHz.
I tried setting BUS speed manualy to x100MHz with no result, also I tried to increase it to x110MHz to compensate the loss but again.. no result. It never reaches x100MHz.
I tried to reset CMOS several times - no result.
I disabled all CPU C-States and EIST - no result.
I make sure that in Windows I am runing PERFORMANCE mod instead of Power Saving - no result.

Doesent matter if I OC the CPU or run it at stock settings it still keeps fluctuating. I tried to update BIOS to F9 but I got some issues that makes me unable to do so by using Q-Flash on the motherboard and also on your website it says that I need to use EFIFLASH.EXE but I dont know how. Everytime I try to run it nothing happens and if I run that .BAT file wich is inccluded with it it says that it cant run on x64-bit version of Windows.
I also tried to update BIOS trough your APP center but that didnt work as well because the moment I click on NEXT your APP will freeze and nothing happens. I was waiting for 30min to be sure that the BIOS updading is not happening in background but it was not.

By the way: I had no issue with this around 8 months ago but since then I never went into BIOS or checked CPU-Z untill now.

I dont know if BUS Speed is fluctuating as well when I am in BIOS because I cant see that but I can see CPU frequency and I can see it fluctuating +-100MHz.

You can see it happening on this video I recorded.
https://www.youtube.com/watch?v=RiO8p6c239k

 

[ShintaiDK]

The small change itself is normal. Its due to spread spectrum. It can also be disabled in BIOS. It serves to protect against interference.

 

[VirtualLarry]

Also, software measurement error.

 

[WereCat]

The small change itself is normal. Its due to spread spectrum. It can also be disabled in BIOS. It serves to protect against interference.

6MHz difference on BUS doesent seem normal. That makes over 100MHz difference in total when OC.

If it was 99.x to 100.x that would be OK but 94-99?

 

[ShintaiDK]

It looks normal in the video.

But you can try disable spread spectrum in BIOS if it bothers you and then see if it keeps doing it.

 

[Insert_Nickname]

6MHz difference on BUS doesent seem normal. That makes over 100MHz difference in total when OC.

If it was 99.x to 100.x that would be OK but 94-99?

Firstly, try disabling "CPU Spread Spectrum" in the BIOS/UEFI. BCLK frequency should then be very close to 100MHz.

Edit; Shintai beat me to it...

 

[WereCat]

It looks normal in the video.

But you can try disable spread spectrum in BIOS if it bothers you and then see if it keeps doing it.

Firstly, try disabling "CPU Spread Spectrum" in the BIOS/UEFI. BCLK frequency should then be very close to 100MHz.

Edit; Shintai beat me to it...

OK, so I tried to disable it but I havent found it so I tried to google where it is and I found this on one of other forums:

"Probably the same reason that it happens in Gigabyte's Z77X boards. It's because Gigabyte doesn't allow us to turn of Spread Spectrum, which is known to cause BCLK fluctuations. We're not sure it's spread spectrum, but it's a common culprit and we can't turn it off in Gigabyte motherboards, for whatever reason."


EDIT:
I installed BETA BIOS F10b and there is option for Spread Spectrum, however it cant be disabled. I can set it to AUTO or change the % from 0.01% to 0.50%. I am assuming the lowest possible should be closest to disabling it so when I set it to 0.01% I am still getting the same fluctuation as I got before.

So looks like that Spread Spectrum is really the thing that is causing it but I am unable to disable it.
Thanks for your help, now I at least know whats going on.