Question My cpu speed is stuck at 0.77 Ghz for some days. What could be the problem?

raunakFIX

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1) Laptop's fan stopped working. It spins for a second, there is a noise and it stops. This keeps repeating. I am using a cooling pad for laptop and there is no heating issue so far. Idle state temperatures are 35-40 deg C. When I use moderately, the temperature goes to 45 C. And when I run an average graphics game, the temperature of GPU goes to 65 to 70 C and for CPU upto 72C.

2) I have ran Throttlestop and it shows BD PROCHOT in red under limits. When I uncheck BD PROCHOT, the CPU overclocks at 2.6Ghz at high performance.

I have a lenovo flex 2-14. Intel core i5-4210U @ 1.7GHz with turbo boost to 2.4Ghz.

3) I have cleared all the dust from laptop using a blower, the best i could do. Tried removing the battery and plugging back in.

What could be the main cause? Is it only because the internal fan is not working? But the temperatures are normal, so I don't understand the reason of CPU speed getting stuck at minimum. Can someone help troubleshoot?
 

raunakFIX

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it looks fine, so that throttling is comming from dead cpu fan
Is that even possible? Because the temperatures are fine. It doesn't make sense that CPU will limit its speed to minimum when the temperatures are fine. Could there be a secondary issue? What do you think?
Well I certainly hope that it's just because of the dead fan and replacing it would fix the issue. Just wondering if there could be another cause.
 

uWebb429

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When you use ThrottleStop to clear BD PROCHOT and run your computer at its full rated speed, how are your temperatures?

BD PROCHOT allows other sensors within your computer to throttle the CPU. If your CPU temperature at full speed is OK then I would use ThrottleStop and I would ignore this problem.

Replacing the fan might fix this problem but it might not. No one knows for sure what sensor is triggering BD PROCHOT throttling. Are you sure the fan is not running when benchmark testing at full speed? The fan might be programmed to turn itself off because at 800 MHz, you do not need a fan.

Were you running Speed Fan before you started having this problem? If it does not fully support your computer, it could also be a reason why your fan is not working properly.
 

raunakFIX

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When you use ThrottleStop to clear BD PROCHOT and run your computer at its full rated speed, how are your temperatures?

BD PROCHOT allows other sensors within your computer to throttle the CPU. If your CPU temperature at full speed is OK then I would use ThrottleStop and I would ignore this problem.

Replacing the fan might fix this problem but it might not. No one knows for sure what sensor is triggering BD PROCHOT throttling. Are you sure the fan is not running when benchmark testing at full speed? The fan might be programmed to turn itself off because at 800 MHz, you do not need a fan.

Were you running Speed Fan before you started having this problem? If it does not fully support your computer, it could also be a reason why your fan is not working properly.
When I clear BD PROCHOT using throttlestop, the idle state CPU temperatures are staying between 36-41C at max CPU speed. However, I tried running Cossacks 3 with BD PROCHOT unchecked and the laptop would just power off in about 5 seconds after the game is launched. I tried this 3-4 times and ended with same result - immediate power off. I checked the temperatures just before it powers off and the GPU temperature was 65-68 C, CPU temperature was 67-70C. It should only turn off when the CPU reaches 100C, so that got me really puzzled.
And then I tried running the game with BD PROCHOT, i.e. at 800Mhz and it doesn't turn off. The GPU temperature reaches 73C and CPU 70C within 1 minute after launching the game. The point is that the laptop doesn't powers itself off. So I guess overclocking CPU is not working here? I am not sure what's happening. But I certainly cannot leave BD PROCHOT unchecked due to this.
Yes, the fan isn't running. It tries to run every 5 seconds and the stops in a second with a noise, like it's stuck or isn't getting enough power or something.
But sometimes the fan suddenly starts to run smoothly with a faint noise but with very low speed, i.e. the lowest speed possible. Like right now, the fan is running at the lowest speed and my CPU is at 0.77Ghz only. And I just ran Cossacks 3 again to check the temperatures at max CPU speed, the fan speed didn't increase or anything. Neither could I feel the heat dissipating from the outlet.
Speed fan is actually not compatible with my laptop i guess. Because it never shows me the fan speed. It just says that SCSI is disabled by user or iaStorA.sys is installed. I basically just use it to monitor CPU and GPU temperatures along with other software. So there is no way that speed fan is causing the downfall of my cooling fan as it doesn't even identify it.
 

uWebb429

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and the laptop would just power off
Disasbling BD PROCHOT and trying to run your CPU at its rated speed is not overclocking. Is your battery dead? It sounds like your power adapter is not able to supply enough power to run your computer at its rated speed. A properly engineered laptop should never be BD PROCHOT throttling or shutting down when loaded.
 

raunakFIX

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Disasbling BD PROCHOT and trying to run your CPU at its rated speed is not overclocking. Is your battery dead? It sounds like your power adapter is not able to supply enough power to run your computer at its rated speed. A properly engineered laptop should never be BD PROCHOT throttling or shutting down when loaded.
I forgot to mention earlier that when I disable BD PROCHOT and run TS benchmark in Throttlestop, a "POWER" limit in red starts blinking every few seconds. It says PL2 under core limit and when I connect to AC, PL2 shows up under GPU limit as well. I have no idea what it means.
No, the battery isn't dead, it works just fine even after 6 years. Battery wear level 40%.
Also, one weird thing happened today when I woke my laptop from sleep. First thing I did was to open throttlestop and everything was normal, i.e. BD PROCHOT was not triggered and the CPU was running at maximum speed. But after 5 minutes, BD PROCHOT got triggered again and it's been like that since.
I wish I knew which sensor is triggering that or there was some way of finding out.

Edit: I was running TS Benchmark again with BD PROCHOT disabled and when I stopped the benchmark, everything went back to normal again, i.e. BD PROCHOT got disabled on its own, not showing under limits anymore. I don't know what's going on with my laptop. It's been running fine since 30 minutes at max CPU. But I am having a feeling that the problem will come back again as I haven't solved it yet.

So if you have any input or suggestions, please help. Thank you for your time.
 
Last edited:

uWebb429

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https://ark.intel.com/content/www/us/en/ark/products/81016/intel-core-i54210u-processor-3m-cache-up-to-2-70-ghz.html

The 4210U is a low power CPU with a 15W TDP rating. When you see PL1 or PL2 or Power flashing red in ThrottleStop, this indicates that CPU performance is being reduced to keep power consumption at or below 15W. Power limit throttling like this is normal. Open the ThrottleStop TPL window to see what the PL1 and PL2 power limits are set to.

Some laptops adjust the turbo power limits. These power limits can be reduced automatically when you switch to battery power. This helps protect the battery from being damaged.

It is not a good idea to run a full load stress test while on battery power with BD PROCHOT disabled. Your battery was not designed for this. Your laptop could instantly shut off to protect against damage.

Some laptops are deliberately shipped with small power adapters that cannot fully power a laptop. During peak demand when plugged in, they depend on battery power to supplement the inadequate power adapter. Manufacturers came up with this scheme so they could ship a smaller power adapter. That saves them money and many consumers like having a smaller power brick that they can fit in their purse.

A battery with 40% wear might still work OK during normal use but it might not be OK during a full load stress test. Some batteries or power adapters are capable of sending BD PROCHOT throttling messages to the CPU.

I am having a feeling that the problem will come back again as I haven't solved it yet.
Once BD PROCHOT throttling starts to happen, it almost always comes back. When external sensors get dirty or start to fail, the throttling problems that they create can be intermittent. A small amount of dust that has built up over time can cause a sensor to randomly short out.

Sensor types and location are not publicly documented by any of the major manufacturers.
 
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raunakFIX

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Dec 7, 2015
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https://ark.intel.com/content/www/us/en/ark/products/81016/intel-core-i54210u-processor-3m-cache-up-to-2-70-ghz.html

The 4210U is a low power CPU with a 15W TDP rating. When you see PL1 or PL2 or Power flashing red in ThrottleStop, this indicates that CPU performance is being reduced to keep power consumption at or below 15W. Power limit throttling like this is normal. Open the ThrottleStop TPL window to see what the PL1 and PL2 power limits are set to.

Some laptops adjust the turbo power limits. These power limits can be reduced automatically when you switch to battery power. This helps protect the battery from being damaged.

It is not a good idea to run a full load stress test while on battery power with BD PROCHOT disabled. Your battery was not designed for this. Your laptop could instantly shut off to protect against damage.

Some laptops are deliberately shipped with small power adapters that cannot fully power a laptop. During peak demand when plugged in, they depend on battery power to supplement the inadequate power adapter. Manufacturers came up with this scheme so they could ship a smaller power adapter. That saves them money and many consumers like having a smaller power brick that they can fit in their purse.

A battery with 40% wear might still work OK during normal use but it might not be OK during a full load stress test. Some batteries or power adapters are capable of sending BD PROCHOT throttling messages to the CPU.


Once BD PROCHOT throttling starts to happen, it almost always comes back. When external sensors get dirty or start to fail, the throttling problems that they create can be intermittent. A small amount of dust that has built up over time can cause a sensor to randomly short out.

Sensor types and location are not publicly documented by any of the major manufacturers.
BD PROCHOT hasn't triggered since that day. I guess I am contented for now. I will just replace the cooling fan in the coming days. Yeah, I checked the power limits, PL1 is 15 W and PL2 is 25W. I understood your point, makes sense.
I will keep this thread unresolved since the problem got fixed on its own and like you said it may come back. If it comes back, I will continue this thread as it is. Thank you very much for your time.
 

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