CPU blocked at minimum speed after deactivating battery

Hello everyone,

I have a problem with my Asus TP300LA laptop and I was hoping someone might give me a hint.

Recently it's charger controller went wrong. It wouldn't even run on AC. To fix it completely I would have to get a new motherboard. Since I was about to buy a new laptop, I chose a cheaper repair, the battery was deactivated and it now only runs with AC power.

The problem is that the CPU is running only at 0,8 GHz on Windows 10. If I run Windows 10 on safe mode the cpu does go all the way up to 1,9 GHz (i3-4030u).

To make sure this wasn't a problem with some Windows 10 update or its drivers, I reinstalled a clean copy of Windows 10 in a spare HDD. The cpu still doesn't go higher than 0,8 GHz.

I read online that some laptops will lock at the lowest speed temporarely when the battery is flat even having AC power coming and I think my computer must be doing the same.

Having it running only at 0,8 GHz makes it pretty much impossible to use.

Does anyone know how to deactivate windows instructions to reduce speed in this situation?

(By the way, this is not a throttling issue for sure. Even if I put my fingers on the ventilation area under the screen while opening several programs it barely gets warm. Also the laptop's interior is completely clean and yesterday while installing the new copy of W10 it was even running without it's cover, it doesn't get hot.)

Thank you for your help

Hello @Caledon Ken , thank you very much

Yes, I didn't remember to mention that.

In my SSD (old installation) I tried going around them in every way, shape and form I could think of. Even setting the cpu's lowest state at 100% and pretty much changing all options which would give more performance and more energy comsumption, but it did not work.

In the HDD Windows 10 (fresh installation done yesterday just for testing) I just checked to see how the settings were but they're ok, like they should, since it's a fresh OS. In the TDP options it was set to run at 1,9 GHz, the cooling was in active mode although it probably doesn't make much difference since the laptop doesn't even get warm.

Since I installed a fresh copy of Windows 10 yesterday and the cpu speed keeps locked at its lowest I suppose it is some windows instruction which we aren't supposed to change. But I'm hoping there's someway to do it on the registry.

Caledon Ken said:

Hopefully another member will join in. I'm unaware of registry settings that by default limit CPU.

You said you deactivated the battery, what did you do to make this happen?

Yes. Sometime ago I was using the laptop and battery was just below 40% so I plugged in the AC.

Several minutes after I noticed that the battery was about 25%. I checked if the charger was plugged and it was. Then I noticed on Windows that it indicated that it was plugged to AC but not charging. I disconnected the charger, reconnected, tried on another wall plug... all the usual stuff, but nothing fixed it.

When the battery was depleted I couldn't turn on the laptop anymore, even using AC.

At first the suspect was the charger but after connecting an universal charger the laptop still wouldn't charge and wouldn't turn on.

I took it to a local hardware shop and they tried to fix it but the new charging controller would work for a few hours and eventually would fail. The way to fix it entirely was to get a new motherboard.

The cheapest solution was to change it into a "AC only" laptop. It lost it's portable advantagens but that wasn't too bad since I was about to get a new laptop anyway and my goal at this point was to have a runnable/backup computer.

I just wished that even as a "desktop laptop only" it could maintain a basic level of performance at 1,9 GHz. Using it blocked on 0,8GHz is just too slow.

Thank you for your help

bro67 said:

A bad sensor is causing [FONT="]BD PROCHOT to throttle down the CPU. You can use Throttlestop to disable BD PROCHOT, since you would need a new motherboard and those can run around $100 USD on eBay. You can download Throttlestop from Majorgeeks.com (trusted). [/FONT]https://www.majorgeeks.com/files/details/throttlestop.html Info on Throttlestop. Download ThrottleStop | TechPowerUp

That sounds good. I already had heard about Throttlestop.

I'm going to check it.

Thank you very much

Caledon Ken said:

Please post back. Very interested in results.

Here goes... and I got good news....

bro67 said:

A bad sensor is causing BD PROCHOT to throttle down the CPU. You can use Throttlestop to disable BD PROCHOT, since you would need a new motherboard and those can run around $100 USD on eBay. You can download Throttlestop from Majorgeeks.com (trusted). https://www.majorgeeks.com/files/details/throttlestop.html Info on Throttlestop. Download ThrottleStop | TechPowerUp

@bro67 , again, thank you very much.

I did exactly what you recommended. I had a few difficulties getting ThrottleStop to run but after it did disabling
BD PROCHOT did the trick. The CPU now varies between 0,8GHz and 1,9GHz, just like it's supposed to do.

Thank you both for your help

GustavoAlmeida said:

...disabling BD PROCHOT did the trick. The CPU now varies between 0,8GHz and 1,9GHz, just like it's supposed to do.

Thank you for reporting your results. Every time a thread on this subject crops up I follow it with interest, hoping for an explanation on a rare but puzzling problem I have on one machine. This is the first thread I've seen that has resolved this .80GHz throttling question.

In my case the System One in 'My Computer' below will occasionally get stuck at .80GHz for no apparent reason. Being a rare occurrence it's difficult to track down the cause, but most often is seen when resuming from hibernation (so can't be temperature related). I tend to never shut down this PC, rather I close the lid and hibernate when done.

Paradoxically, unplugging the power cord can sometimes restore normal speed, but after using this fix a few times it ceases to work. A Restart will always fix it. I'm not so much looking for a permanent fix as I can always restore normal operation, but not knowing what caused it has been like an itch I couldn't scratch. bro67's explanation makes complete sense. In my case I suspect it's not the sensor itself, but a register associated with it that gets corrupted. Now I can relax and stop worrying about the cause of my (rare) issue.