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33 Posts

01-04-2021

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  • Message 1 of 22

P340 Tiny processor locked at 800 Mhz

2021-01-04, 18:01 PM

After some months of using P340 Tiny with i9-10900T processor I suddenly experienced a sudden drop in perfomance.

Turned out the processor throttled down for some reason, and the reason was not overheating.

 

I was trying everithing - from Power Management settings in Win10 to resetting BIOS to default settings. But long story short - what helped: unplugging the power supply cord from the PC and plugging it back again. Me personally turned it 180 degrees, but not sure it is necessary. 

 

Probably it has something to do with clearing Fast Boot cache in BIOS, tho I am not sure unplugging does that.

 

So in case you suddenly experience processor severely slowing down for no reason - try unplugging the power adaptor.

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900 Posts

01-14-2014

US

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  • Message 2 of 22

Re:P340 Tiny processor locked at 800 Mhz

2021-01-04, 20:22 PM

I'm quite surprised that the i9-10900T processor was locked at 800MHz before having to manually pull AC power.  Let us know if you encounter this problem again so we can investigate it further. 

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33 Posts

01-04-2021

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  • Message 3 of 22

Re:P340 Tiny processor locked at 800 Mhz

2021-01-04, 21:56 PM

Ofc, I will monitor it closely now. 

i have updated BIOS and Intel Management firmware to latest today, for some reason Vantage did not offer those updates tho they are clearly available for manual install. Also I have Intel XTU now so if issue repeats will gather more detailed info.

 

And as a Lenovo engineer do you have a explanation for what happened and what could cause it?

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33 Posts

01-04-2021

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  • Message 4 of 22

Re:P340 Tiny processor locked at 800 Mhz

2021-01-05, 9:06 AM

Today in the morning - the same behaviour again right from the start, please check attached screen shot.

 

AIDA64 reports fixed 800 Mhz clock and Intel XTU reports active thermal throttling so the temp is below 40C and the fans are silent.

 

Please advice?

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33 Posts

01-04-2021

RU

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  • Message 5 of 22

Re:P340 Tiny processor locked at 800 Mhz

2021-01-05, 9:10 AM

As before - unplugging the power adaptor solved the issue.

 

The only unusual thing I did last evening is updating the BIOS. And the time the issue happened before was right after BIOS update as well, so those are definetely connected.

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33 Posts

01-04-2021

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  • Message 6 of 22

Re:P340 Tiny processor locked at 800 Mhz

2021-01-06, 7:33 AM

Same this morning again. Seems it is bacoming an annoying issue. If I was to guess - it was introduced in Dec BIOS update M2WKT3EA.

 

Any help Lenovo?

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33 Posts

01-04-2021

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  • Message 7 of 22

Re:P340 Tiny processor locked at 800 Mhz

2021-01-06, 10:01 AM

Ok one more post. I think I know the source of the problem - check the screenshot.

For some reason BD PROCHOT line is being activated forcing the processor to throttle down - check the red line on the right.

If I remove the relative checkbox - perfomance returns to normal.

 

Now it is up to Lenovo to point out why this happens and what to do with it. Could be HW fault, but this is unlikely as it is easily cured by unplugging and plugging back in power adaptor, untill the next power-off.

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4838 Posts

02-22-2010

NC

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  • Message 8 of 22

Re:P340 Tiny processor locked at 800 Mhz

2021-01-06, 16:17 PM

Is there something missing from your Throttlestop image?  I don't see anything showing temp logs or the prochot signal.  It's hard to make any interpretations based on the data in that image, which seems to indicate a max temp of 50C...which is well below prochot.  Also, the intel XTU screenshot from earlier is basically unreadable due to the resolution.  Were you seeing prochot being asserted in XTU as well?

 

The BIOS readme doesn't offer a ton of detail on the changes added in the different BIOS versions, but I see nothing in the recent BIOS updates that would indicate any sort of change to CPU power levels, thermals, VR, etc.  There was a CPU microcode update added back in version 3A, but that seems to be several versions older than the one you're claiming caused the issue.

 

Were you using Throttlestop or XTU to make any changes to the CPU function on your system?




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33 Posts

01-04-2021

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  • Message 9 of 22

Re:P340 Tiny processor locked at 800 Mhz

2021-01-06, 16:52 PM

Sorry, did not notice that uploaded file got distorted. Probably too big.

 

Ok, first: I did not do any changed to processor paramerters using XTU or ThrottleStop, was using those only to monitor.

 

Please check attached screenshots.

 

1. 2 screens from ThrottleStop - one with BD PROCHOT active - there is red blinking indicator when it is working, I put it in red frame. Another of normal operation - BD PROCHOT is not blonking. Also there is a visible difference in VID and PKG power.

 

2. XTU & AIDA64 combined shot - white window thats AIDA64 after performing processor test. You can clearly see 800 Mhz speed under stress load. Below in black window is XTU indicating thermal throttling active due to BD PROCHOT activation.

 

My suggestion with BIOS update is simple - I was using PC for several month just fine, and after the update the issue appeared and it is re-occuring after every power-off.

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33 Posts

01-04-2021

RU

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  • Message 10 of 22

Re:P340 Tiny processor locked at 800 Mhz

2021-01-06, 16:53 PM

PROCHOT

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