Handbrake cpu clock multiplier

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herald128bit
Posts: 3
Joined: Wed Mar 17, 2021 4:31 pm

Handbrake cpu clock multiplier

Post by herald128bit »

Help !!

Odd CPU clock multiplier behaviour when using handbrake;

When I set CPU clock multiplier to 50 and run handbrake, my cpu clock runs at 4.7GHz stable
When I set CPU clock multiplier to 49 and run handbrake, my cpu clock runs at 4.6GHz stable
but...
When I set the CPU clock multiplier to 48 and run handbrake, my cpu clock runs at 4.8GHz stable

I'm getting good 100% cpu utilisation in all cases

please help.... is this anything to do with avx ?

handbrake 1.3.3
Windows 10
Intel i7 - 9700K
rollin_eng
Veteran User
Posts: 3928
Joined: Wed May 04, 2011 11:06 pm

Re: Handbrake cpu clock multiplier

Post by rollin_eng »

This sounds like a bios/os issue, HB cannot change your cpu speed.
Deleted User 13735

Re: Handbrake cpu clock multiplier

Post by Deleted User 13735 »

It's a mystery ...
herald128bit
Posts: 3
Joined: Wed Mar 17, 2021 4:31 pm

Re: Handbrake cpu clock multiplier

Post by herald128bit »

I have run some more tests and for some reason this does appear to be a handbrake issue...

running other applications, including userbenchmark, give full clock multiplier sustained. It appears that only with HB that the CPU multiplier drops down.
Just ran another test multiplier 51 = 5.1GHz
Games happy at this speed.
HB, drops to 46 = 4.6 GHz

Please help....!!! I am stuck on what this could be. Any possibility it could have something to do with AVX ?
Woodstock
Veteran User
Posts: 4105
Joined: Tue Aug 27, 2013 6:39 am

Re: Handbrake cpu clock multiplier

Post by Woodstock »

Probably your motherboard responding to a heat issue. Are you monitoring your CPU core temps?
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s55
HandBrake Team
Posts: 9973
Joined: Sun Dec 24, 2006 1:05 pm

Re: Handbrake cpu clock multiplier

Post by s55 »

Intel CPU's will clock lower when AVX instructions are used. This is the correct behaviour. Some motherboards have this as a septate AVX Offset feature. Some don't

I wouldn't recommend adjusting it. IT's offset for a reason. AVX instructions are complex and have a high power utilisation, thus heat output. We've seen a lot of people try overclock and run into hard limits trying to overclock it.

It's not uncommon to see people have to dial their overclocks back 2~300mhz or more to get the system stable for this kind of workload.
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