• Welcome to Overclockers Forums! Join us to reply in threads, receive reduced ads, and to customize your site experience!

More vcore for x264/x265 encoding ?

Overclockers is supported by our readers. When you click a link to make a purchase, we may earn a commission. Learn More.

Kenrou

Member
Joined
Aug 14, 2014
So, Prime95/Realbench stable 12h 4.7ghz 1.32v, but seemingly need 1.34v/1.35v to encode x264/x265 ? Don't remember having to up the voltage with my old 8370, is Intel that different or is there maybe something wrong with the encoder itself ?

Using Handbrake and Internet Friendly Media Encoder.
 

Woomack

Benching Team Leader
Joined
Jan 2, 2005
It simply means that CPU wasn't fully stable. It's also reason why 12h stability tests are waste of time. Better make couple of tests for ~1-2h each than leave it for 12h+ in one test. Simply if you fill the RAM and stabilize max temps after let's say 1-2h then next couple of hours won't change much.
 
OP
Kenrou

Kenrou

Member
Joined
Aug 14, 2014
But thats what i did, ~30m between voltage bumps (both Prime95 blend and Realbench full 16gb ram) and then 12h stretch on the final, for all intents and purposes this OC was stable. Doesn't crash on anything else that i noticed, Fold and Seti slog away like usual, Metro 2033 Redux is giving me a headache (librarian maze atm) and temps as high as Prime95 so... i don't get it :confused:
 

EarthDog

Gulper Nozzle Co-Owner
Joined
Dec 15, 2008
Location
Buckeyes!
Just not stable there... add some voltage. Handbrake may not use the same instruction sets, etc.
 
OP
Kenrou

Kenrou

Member
Joined
Aug 14, 2014
Ok testing done, to encode h264/h265 100% stable i need a whooping 1.38v, thats +0.06v :bang head should i make profiles in BIOS, normal 24/7 4.7ghz 1.32v and another just for encoding ? Computer doesn't crash in anything else i throw at it at the lower voltage :confused:
 

ATMINSIDE

Sim Racing Aficionado Co-Owner
Joined
Jun 28, 2012
Why so complicated? Just run where the voltage needs to be for encoding all the time
 
OP
Kenrou

Kenrou

Member
Joined
Aug 14, 2014
1.38v is my normal 4.8ghz overclock (now to be renamed stable to everything except h264) :rofl: yeah you're right, why complicate. Thnx again :thup:
 
OP
Kenrou

Kenrou

Member
Joined
Aug 14, 2014
Found out the problem i think, since i got the Skylake i stuck to Prime95 Blend and i completely forgot i had my ram overclocked (duh! :bang head). Back to stock settings and new BIOS 1701, 26.6 went down to 4.7ghz 1.3v/4.8ghz 1.36v, 28.9 4.7ghz 1.32v/4.8ghz 1.38v 2h mark BUT and this is the funny thing, drops cores on small FFT pretty much straight away. In the process of more testing now...


EDIT: 26.6 passes blend + small FFT, 28.9 passes blend fails small FFT, Realbench freezes as soon as the coding part starts regardless, i can safely assume its AVX screwing this up ?
 
Last edited:

cyberfish

Member
Joined
May 23, 2008
Location
London, England
AVX significantly increases the power consumption of the CPU because it does roughly twice the amount of work per instruction compared to SSE, so yes, most likely.

It just means your old voltage wasn't stable. You just haven't been stressing your CPU to its full potential.
 
OP
Kenrou

Kenrou

Member
Joined
Aug 14, 2014
"Full potencial" means having to stop using Prime95/Aida64/IBT/OCCT because only Realbench and x264 stress it that hard on AVX. On a interesting side note, the only AVX i ever used was on x264 coding :mad:
 

cyberfish

Member
Joined
May 23, 2008
Location
London, England
"Full potencial" means having to stop using Prime95/Aida64/IBT/OCCT because only Realbench and x264 stress it that hard on AVX. On a interesting side note, the only AVX i ever used was on x264 coding :mad:

I use quite a few programs (not synthetic benchmarks) that use AVX, but then I do scientific computing.

AVX is becoming more and more common now that all new CPUs have supported it for quite a few years now, and it offers a huge speed boost especially on post-Sandy Bridge CPUs. Pretty sure most rendering programs use it as well. Maybe even Photoshop? I wouldn't be surprised if games start using it for physics simulation, too, if they haven't already. AVX2 (Haswell and above) support integer vector instructions, so it's probably useful for things like compression as well.

At this time I personally wouldn't consider a CPU stable if it's not stable with AVX.