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Punch Card
Posts: 29
Registered: ‎06-18-2017
Location: US
Message 41 of 61 (1,119 Views)

Re: P51 - Heavy Throttling on Battery

I see this as well on my P51..  Only way to get it out of 800Mhz slow mode on battery is by unchecking BD PROCHOT in throttle stop.

 

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Posts: 11
Registered: ‎02-24-2014
Location: Houston, TX
Message 42 of 61 (1,110 Views)

Re: P51 - Heavy Throttling on Battery

Doing a search for 'BD PROCHOT Lenovo' seems to reveal that this has been an issue across multiple Lenovo product lines for years. Not very encouraging to be honest, hopefully there is a firmware fix that can solve this.

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Posts: 13
Registered: ‎04-24-2017
Location: US
Message 43 of 61 (1,097 Views)

Re: P51 - Heavy Throttling on Battery

Very interested to see what they find, might be able to finally replace my aging mbpr!  The P51 was a great machine other than this quirk.

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Lenovo Staff
Posts: 3,850
Registered: ‎10-29-2009
Location: NC
Message 44 of 61 (1,041 Views)

Re: P51 - Heavy Throttling on Battery

We found a bug in ECFW (Embedded Controller Firmware) version 1.04.  It is fixed in ECFW 1.05, but I don't know the release date yet.  (ECFW is updated as part of BIOS update.)

 

The bug is:  once the ECFW limits the CPU frequency to prevent battery power consumption too high, the CPU speed ends up locked to ~800MHz and never recovers until AC adapter is attached.  See screenshot of bug:  https://www.dropbox.com/s/s3ckgrv40i54m6d/ECFW21.PNG?dl=0

 

The fix is:  ECFW will unlock CPU speed once the battery power consumption goes under the limit.  See screenshot of fix:  https://www.dropbox.com/s/bwx8li5lymvq8jz/ECFW22.PNG?dl=0

 

One thing I want to be clear about.  P51 cannot perform same on battery as it can on AC.  Some throttling in some situations is required to avoid battery power consumption too high situation.

 

SCSI Port
Posts: 27
Registered: ‎01-08-2013
Location: Norway
Message 45 of 61 (1,029 Views)

Re: P51 - Heavy Throttling on Battery

[ Edited ]

Thank you!

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Posts: 11
Registered: ‎02-24-2014
Location: Houston, TX
Message 46 of 61 (1,012 Views)

Re: P51 - Heavy Throttling on Battery

So, since this is a critical issue for myself needing to be mobile, can I sign some sort of waiver and get the update any sooner?
Punch Card
Posts: 29
Registered: ‎06-18-2017
Location: US
Message 47 of 61 (1,001 Views)

Re: P51 - Heavy Throttling on Battery

For now using throttle stop and unchecking bd proc hot works for me 

Punch Card
Posts: 29
Registered: ‎06-18-2017
Location: US
Message 48 of 61 (962 Views)

Re: P51 - Heavy Throttling on Battery

I noticed you were using Prime95 on the stress test.. Smiley Happy

 

Are you seeing 100C temps on the CPU when doing those tests? in other words, is that the expected peak?

Lenovo Staff
Posts: 3,850
Registered: ‎10-29-2009
Location: NC
Message 49 of 61 (952 Views)

Re: P51 - Heavy Throttling on Battery


PaulMurdock wrote:

I noticed you were using Prime95 on the stress test.. Smiley Happy

 

Are you seeing 100C temps on the CPU when doing those tests? in other words, is that the expected peak?


 

No, I never see anything near 100C on battery.  I don't think it can be expected to see that kind of temperature (and performance) on battery.

Punch Card
Posts: 29
Registered: ‎06-18-2017
Location: US
Message 50 of 61 (943 Views)

Re: P51 - Heavy Throttling on Battery

How about when on A.C.? My p51 gets up to 100C.. it's my 2nd one,  first one was replaced and 2nd one had the issue, and a service tech has replaced the heat sink assy. Still 100C.. 

 

It appears P51 design allows for 100C on AC.

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