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6850K CPU Throttling Cores

1K views 15 replies 4 participants last post by  c0zm0 
#1 ·
Greetings Guys.

I Have Increase Core Voltage From 1.25 to 1.30v to get more Stability, but When passing Prime95 test to the system, I have noticed that now the CPU is throttling his Cores.

First, as some of you suggested, we thought it may be Thermal Throttling, but after monitorizing the CPU with CoreTemp, none of the cores passed 71 Cº so that possibility is very unlikely.

So now I think that due to the power demand increase, something in the OS or the Bios is limiting the power comsumption and force the cores to throttle when the CPU demands more power.

As It's my first Overclock I'm a bit lost here, any clue about what may be causing this throttling?

Many Thanks.
 
#3 ·
When you say throttling, how low is the multiplier dropping?
Depending on the version of Prime95 that you run, if it uses the AVX instructions (all recent versions do), your motherboard has a setting that will automatically downclock your CPU to keep it from drawing too much power when using AVX instructions. That setting is enabled by default on my motherboard, it's called AVX Ratio Offset. I need to set it to 0 if I don't want the CPU to downclock. When at stock for instance, the multiplier would drop from 36x to 35x as soon as Prime95 would start running a test.
 
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#4 ·
Thanks Guys for answering.

Emmanuel, I'm at work now and Can't check right now, but If I remember correctly I have version 2.66 and the last 2.8X . Throttling effect is the Same when I run both versions.

About the Multiplier, I'm not tracking it ( Don't know how to track it, Honestly, maybe CPU-Z?), What I use is Coretemp 1.4 To Check Temp and Load on the six cores. I presume is a case of Throttling because load pass from !00% to Idle (2-3%) in some cores., then these cores pass to 100% and the effect pass to other cores.

Now that you mention the AVX Ratio Offset, I remember having set it to 3, because I was following an Internet guide. Will set it to 0 like you did and check If the problem is there.

Cozmo, Will also check the feature you suggested In Windows, hope solution is as simple as that.

Many thanks guys, will keep you informed.
 
#5 ·
Ok I have Changed Power Profile In W10 to a custom one with max CPU usage. Then entered the BIOS and set the AVX Offset Multiplier to min I Could that was 1, I mean that I tried to input 0, but the Bios just changed it to 1.

Downloaded Intel XTU and ran Prime95 v289 . Al Cores Stressed properly, but Intel XTU said that the number of Active Cores Was 3. On the other hand, CoreTemp was showing that the 6 cores were Stressed, please check PIC:



Also, sometimes Prime95 says "Unable to Detect some of the Hyperthreaded logical CPUs" And mess with the number of cores my system has. This is begining to give me a Headache, any clues pls Guys?

Many thanks
 
#6 ·
Does resetting your BIOS to default bring back your 4th core? There must be a TDP setting somwhere in your BIOS, it's currently set to 140Watts judging by your screenshot. You could try setting it to Auto or higher than 140W. There could also be a setting for Max Amps. One more thing , have you tried using this, https://www.techpowerup.com/downloads/2815/throttlestop-8-30 ?
 
#7 ·
Quote:
Originally Posted by c0zm0 View Post

Does resetting your BIOS to default bring back your 4th core? There must be a TDP setting somwhere in your BIOS, it's currently set to 140Watts judging by your screenshot. You could try setting it to Auto or higher than 140W. There could also be a setting for Max Amps. One more thing , have you tried using this, https://www.techpowerup.com/downloads/2815/throttlestop-8-30 ?
As you can see Its my first OC
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and I'm still newbie on this. First time I noticed that Power Limitation was when you pointed at it
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. Definitively, 140W Is too low for an Overclocked 6850K, It's very likely that the problem is there.

Will look on it, hope I could find the setting., Many thanks Cozmo, wont be able to work on the PC Till tomorrow but will keep you Informed. Anyway with the tweak with the Windows power management, and the Offset setting, the throttling seems to have gone.

Btw 6850K has 6 cores 12 threads
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#9 ·
OK sorry guys I have been some Days out and could not work on the PC, heres a little update on the situation.

First I have lowered a litte the CPU volt to 2.850v And set Cache volt to Auto. and Raised the current limit in the Digi+ section to 120% just because if the problems were caused from a current shortage. Also enabled All the monitors on Intel XTU. And ran prime95 v289, results were better but still weird.

At first all seemed to run properly, and I thought I finally hitted the JacKpot with the settings:



Although all were running properly, XTU still was showing that active cores were only 3, but It was reporting 100% load on all cores? This is weird, is any kind of reporting error? or 3 of my cores are really not working? Coretemp also shows 6 cores working at 100%, I can't understand this guys, any help pls?

Then 10 mins into the test, one of the cores started to drop performance from 100 to 60% with no apparent cause:



Then, 10 more mins into the test and another core lowered it's performance to 60%:



At this point I decided to Stop the test and surrender, lowered the Overclock to 4.3Ghz and run test Again, with no problem this time. This pic is taken with the test runnning for more than a Hour there I had to stop the test:

.

So I must admit I have no freaking clue on what´s going on with my rig. Anyone have any idea pls?

As allways many thanks for your interest guys.
 
#12 ·
You could try disabling all turbo boost features and all C states to verify the cores are able run at full speed while idle. Also there must a be setting which will let you keep your core speeds/multipliers in sync, it's a feature peculiar to Broadwell-E. Have you tried https://www.hwinfo.com/ to monitor the system?

I vaguely remember XTU not showing the actual number of cores on my rig either, in any case it was not 100% accurate and I no longer use it.
 
#13 ·
Ok cosmo, I won't be at home for 2 days, but when I get back will try your suggestions. I remember seeing the Turbo Set in the Bios, but what are C States? sorry for my newbieness
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That setting you tal about, I presume is "Sync all cores" Is over the multiplier settings and is allready enabled. I'm downloading hwinfo as we speak
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Will see you again in 2 days, thanks my friend.
 
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