Low CPU clock speed even under load

[yogotami]

I have a Dell XPS L502X stock + SSD (core i5-2430 @2.4 GHz) with everything up to date. Basically the clock speed is stuck at 0.8 GHz, making it impossible to watch videos on YouTube because of all the stuttering.

The main problem is because it is inconsistent: yesterday I thought about posting here about the problem and saw someone talking about updating the BIOS, and so I did, because there as an update early june. After the update, it came back to normal (base 2.4 GHz up to 3 GHz on turboboost). But today when I turned it on, it was back with the problem. I didn't change absolutely anything before turning it off. This exact same thing happened some times before (working fine one day to slow in the other).

I have tried a lot of things, that includes changing the power management settings (all I could find), switching on and off the SpeedStep, messing with the intelppm registry entry (that put the clock speed to the base speed, but it didn't change the performance, the videos would stutter and it wouldn't turboboost), switching off all of the non-Microsoft services at msconfig. All of that to nothing.

I do run my laptop only through the AC adaptor (original) because the battery is long dead.

I think it isn't thermal related since it ran full speed just yesterday, might be something about the power delivery, but I don't know how to measure it.

[Oathkeeperspath]

 First thing I would do is check to make sure that the power supply is giving enough power, you can do that with a voltmeter if you're familiar with electricity, Or you can buy another power adapter and power brick offline.  I don't know if this is one of those cases but I've heard of laptops acting up real bad when the battery is completely fried,  might want to look into buying a replacement offline if they offer it.  Any further checking of the actual voltage between the components would require taking the laptop apart and is not something for you to do if you're not willing to take the risk of making mistakes and possibly permanently brick your laptop. I would also check to see if there's been another bio update because the previous update helped somehow even if it was only temporary.

[yogotami]

36 minutes ago, Oathkeeperspath said:

 First thing I would do is check to make sure that the power supply is giving enough power, you can do that with a voltmeter if you're familiar with electricity, Or you can buy another power adapter and power brick offline.  I don't know if this is one of those cases but I've heard of laptops acting up real bad when the battery is completely fried,  might want to look into buying a replacement offline if they offer it.  Any further checking of the actual voltage between the components would require taking the laptop apart and is not something for you to do if you're not willing to take the risk of making mistakes and possibly permanently brick your laptop. I would also check to see if there's been another bio update because the previous update helped somehow even if it was only temporary.

Thanks for your input, I'll try to get a hold on a voltmeter or another power brick to see if anything changes.

For now, buying a new battery is off the table since it's very expensive.

The latest BIOS is the one I mentioned, so there isn't a new version.

[yogotami]

I am dumb. As I said, it might be something about power delivery, and in fact was. The cable that is supposed to be plugged in the AC adaptor wasn't plugged all the way in, I corrected it and it booted just fine (base clock speed and turboboosting). Tried to turn the laptop off and on again and it kept the clock speed on the supposed levels.