BD PROCHOT – CPU running at 34% maximum frequency

BD PROCHOT thermal limiting CPUs detection, workaround, and real fix of a new motherboard

By shauncassells in Windows Insider on
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The following article is about my digging into a performance issue.  It was only resolved with a hardware replacement.  The details below show troubleshooting, a method of detection, and a workaround.

My Dell Precision 5510 is running like a 486!!!

Machine is running super slow.  Sharing and running Hyper-V is unusable.   Task Manager (Ctrl+Shift+Esc) wasn’t showing anything useful.  It was showing 100% CPU utilization but this was on Windows 10.  Doing some more digging with sysinternals processmonitor I noticed the clock speed was fixed at 800mhz.

 Turns out my Intel i5-6300HQ CPU is running at only 800mhz!?!?!! 

CPU Details

System Information CPU Summary 5331% Totals Handles 125m 3,447 GPIJ Context Switch Delta Interrupt Delta Topology 19 13,322 Shaw one graph per CPU

http://ark.intel.com/products/88959/Intel-Core-i5-6300HQ-Processor-6M-Cache-up-to-3_20-GHz

Resource Monitor

Instead of using Sysinternals I remembered the native Windows application Resource Monitor and started using that after multiple reboots and BIOS updates (don’t forget to suspend Bitlocker before a BIOS update).  One of my favorite quotes is a scientist rarely says “EURKA! I have found it”.  Instead they say “Gee that’s funny”.

Resource Monitor File Monitor Help cpu - Total Overview CPU proc Image Memory Disk Net'.wrk 20% CPU U 6760 8280 11072 16880 9580 17100 10268 3840 34% Maximum Fre en Descripti„ Backgrom Win d cum Search Store Settings Calculat„ Microsom Video Am Status Suspenm Suspenm Suspenm Suspenm Suspenm Suspen_ Suspenm Suspen_ Suspen_ Threads CPU backgroundTaskHostexe ShelExperienceHostexe O secure system WnStoreAppexe MicrosoftMsnNewsexe 60 Seconds Service CPU usage

Maximum Frequency

33% is my maximum frequency?  What happened to Intel Burst/Turbo Mode?  Bingle!  Doing some serious digging looks like the CPU is going into thermal panic.  Thermal panic has an official term called BD PROCHOT.

File Monitor Help Overview CPU Memory mage Disk Network 17% cpu Descripti Status 33% Maximum F Th reads cpu Ave rag „

BD PROCHOT

PROCHOT is not the same as BD PROCHOT

PROCHOT is about CPU thermal restriction.  The heat of the CPU is not high… so that isn’t why it is slow

BD = BiDirectional = Components on the motherboard are saying slow the CPU down so they can catch up.

OL'mit Reasons core i5-6300HQ CORE RING EDP 01

Best writeup I found

From <https://linustechtips.com/main/topic/531278-skylake-system-stuck-at-800mhz/>

BD PROCHOT stands for bi-directional processor hot.  This allows other sensors on your motherboard to signal the CPU which forces the CPU to use the minimum multiplier (8).  The CPU behaves exactly the same as if it was thermal throttling but in this case, the CPU temperature is fine.  On some motherboards, it can be either a temperature switch from the voltage regulator or a power consumption switch.  On your motherboard, it is very likely that the Slow Mode switch intended for LN2 users is failing.  The only fix is a new board.  This problem has nothing to do with Windows.  

But what if you can’t (or won’t) replace the motherboard?

Workaround

https://www.techpowerup.com/download/techpowerup-throttlestop/

ThrottleStop is the only free software available that lets a user disable the BD PROCHOT signal path.  When you uncheck BD PROCHOT, that blocks signals from the defective switch getting to your CPU.  A simple fix and after you disable BD PROCHOT, you should be able to exit ThrottleStop and the BD PROCHOT signal path will remain disabled.  ThrottleStop also has an option that you can add to the INI configuration file.

Additional Info

What does a BD PROCHOT affected CPU look like?

core i5-6300HQ VID 0.7241 V 7.97 x 100.174 MHz 798.39 MHz FID 7.97 7.97 7.97 7.97 coc,'o 71.2 73.8 65.2 64.8 CMod 100.0 100.0 100.0 100.0 Chip 100.0 100.0 100.0 100.0 Temp 340C 360C 340C 350C Max 470 C 490C 490C 480C
OL'mit Reasons core i5-6300HQ CORE RING EDP 01

CPU Details

MSR  0x1FC

BD PROCHOT Disabled

t RT MSR Tool EAX MSR Number OxlFC Core 2 3 Copy To Write I w rte I Write I Write I Write MSA Read MSA

BD PROCHOT Enabled

tRT MSR Tool EDX [63.321 EAX (31.01 MSR Number OxlFC Core 2 3 Copy To Write I Write I Write I Write I Write MSR Read MSR

Turns out this was a hardware failure.  This was instantly fixed by a warranty motherboard replacement by Dell.  I should have called in a ticket long before.

Detection method

Hmm there must be a method to see what the current CPU multiplier is or the EAX Number.  I didn’t have time to look it up.  Anyone know how to get this from command line, WMI, or something else?

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Published by shauncassells

Shaun Cassells, Senior Solutions Engineer, 1E Shaun is a Microsoft MVP Windows Insider MVP and executive at Central Texas Systems Management User Group (CTSMUG). Shaun is a frequent speaker at conferences like MMS, Gartner, TechEd Europe, TechEd North America, IT Dev Connections, System Center Rallies, and Systems Management User Groups (SMUGs). Shaun is an award winning blogger syndicated from www.shauncassells.com. Shaun specializes in analysis, optimization, and design of Tactical Solutions to Strategic Business Goals. Prior to joining 1E in 2010, he worked for a Global 100 company as the Configuration Manager Service Owner and Architect. Recently as a Principle Consultant at 1E, he accomplished design, review, and improvements to a variety of Configuration Manager environments from the very small to sites with a half million seats. He provided leadership that created a patented automated application rationalization and usage based OSD mapping solution in use by multiple fortune 500 companies. These days you can find Shaun traveling to help discover, review, and improve business productivity across the world.

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