H.264 reduces my overclock why?

Trunkey · 11 May 2020 at 12:36

So no matter what I set my overclock to as soon as H.264 video encoding starts to run I loose 300mhz from my overclock. It matters not what the overclock is or what the CPU voltage is it just drops from 3.4Ghz to 3.1Ghz or 3.7Ghz to 3.4Ghz or even 4.4Ghz to 4.1Ghz even if CPU Vin is 1.35v

So why is this happening? I'm at a loss!

Spec's as below.

SonicSW20 · 11 May 2020 at 12:49

Probably hitting a thermal or current limit as h264 encoding is a heavy all core load.

Trunkey · 11 May 2020 at 13:02

It does it on Cinebench too I've just noted, its definitely not temp related as the hottest core is only just getting into the 60's with most in the 50's so current or voltage sounds likely, any idea where to start or what the likely culprit is?

ubern00b · 11 May 2020 at 13:28

Not AVX offset kicking in is it?

Taken from a quick Google to explain it:

"Intel has added in an AVX Offset setting, which allows you to set a number of multipliers for the CPU core to drop down to if AVX is engaged. For example, if you set 50x for the Core ratio and -2 or 2 for the AVX offset, you will get a 5GHz overclock while playing games (no AVX) and 4.8GHz when running HandBrake (AVX)."

lsg1r · 11 May 2020 at 13:29

Just a random thought.... are all your cores set to the higher 'speed'.

I know my cpu has slower clocks when all cores are used unless I set it otherwise.

Trunkey · 11 May 2020 at 13:38

lsg1r said:
Just a random thought.... are all your cores set to the higher 'speed'.

I know my cpu has slower clocks when all cores are used unless I set it otherwise.

I've seen some cores with a lower clock speed but I set them all manually to the higher figure so I don't think that's the cause good point to be aware of though.

Trunkey · 11 May 2020 at 13:39

ubern00b said:
Not AVX offset kicking in is it?

Taken from a quick Google to explain it:

"Intel has added in an AVX Offset setting, which allows you to set a number of multipliers for the CPU core to drop down to if AVX is engaged. For example, if you set 50x for the Core ratio and -2 or 2 for the AVX offset, you will get a 5GHz overclock while playing games (no AVX) and 4.8GHz when running HandBrake (AVX)."

I will have a look at this and make sure its set manually to zero.

Trunkey · 12 May 2020 at 12:31

ubern00b said:
Not AVX offset kicking in is it?

Taken from a quick Google to explain it:

"Intel has added in an AVX Offset setting, which allows you to set a number of multipliers for the CPU core to drop down to if AVX is engaged. For example, if you set 50x for the Core ratio and -2 or 2 for the AVX offset, you will get a 5GHz overclock while playing games (no AVX) and 4.8GHz when running HandBrake (AVX)."

Haha! yes it was and it was exactly as you explained, set to auto its value was 3 a quick manual change to 0 and the 4.4Ghz overclock on all cores was solid with no slowing down.