How change CPU multiplier on Lenovo Intel processor?

Question

I bought new Lenovo laptop a week ago. At first it works very well but then suddenly it started to work very slowly. After installing CPU-Z, I found that the CPU multiplier is set to 4 (from 28).

I cannot find any option to change back it to 28 even in the BIOS. I haven't done any heavy tasks such as gaming.

Solution 1

Your problem will be fixed by unchecking BD PROCHOT.

Source "BD PROCHOT is not the same as PROCHOT. If your CPU gets too hot ( PROCessor HOT ) your CPU will slow down to protect itself from damage whether BD PROCHOT is enabled or disabled." So it is safe to uncheck BD PROCHOT and leave it unchecked. The BD PROCHOT setting seems to be common in Skylake CPU's, which is what you happen to have.

The purpose of BD PROCHOT (bi-directional prochot) is to force your CPU to underclock in order to let the entire PC cool down. From what I have found on several forums, it seems the setting is triggered too easily, causing it to throttle down when it doesn't need to be. As well as not turning off once it is cooled down.

BD PROCHOT allows your motherboard to throttle the CPU, rather than leaving that decision up to the CPU itself. PROCHOT will kick in when your CPU reaches it's max TDP which is either 100C or 105C, depending on the CPU. It also sounds like not many motherboards have the BD PROCHOT setting, but for the ones that do, many people have also experienced their CPU getting stuck at something under 1 GHz, usually in the 400-800 MHz frequency range.

You can probably uninstall OBSIDIAN, if you want. It would be nice to experiment and see if the laptop continues to function properly without it. If you wish, you may also leave it installed and just make sure it does not start when Windows boots. Then you can refer to the program in the future if needed.

Solution 2

Thank you @DrZoo I have fixed problem by installing OBSIDIAN program (see attached screenshot) download by link techpowerup. I unchecked "BD PROCHOT" checkbox and it fix problem. After that I can see in cpu-z 28 multiplier.

About "BD PROCHOT" I found this link

BD PROCHOT stands for bi-directional prochot. PROCHOT stands for processor hot which is the signal that is activated within the CPU when it reaches approximately 100C to 105C depending on the model number. This signal is what initiates thermal throttling so the CPU can slow down and keep from over heating. Intel included a bi-directional feature so if something else like a GPU is running too hot, it would be able to send a PROCHOT signal directly to the CPU and force it to cool down so the entire laptop cools down. Very few laptops seem to use this type of throttling. This feature was added for the Asus G51. Disabling this will allow your CPU to continue to run at full speed. Disabling this will not prevent your CPU from thermal throttling at its normal Intel set thermal throttle temperature. By default this is locked and you will need to go into the Options window to unlock it so you can toggle it on and off.

Solution 3

Your processor is an i5-6200U, which is not overclockable. Recent Intel processors with the 'K' suffix like the Core i7-7700K are overclockable. Generally, laptops do not have overclockable processors. The 'U' suffix indicates that it's made for low power consumption. Intel source on naming conventions : https://www.intel.com/content/www/us/en/processors/processor-numbers.html

Comments

[DrZoo]

I do not think you can go into the BIOS or anything to change the multiplier. Laptops generally don't let you overclock. Did you ever see that the multiplier was at 28 before, or are you assuming it was at 28 because that's what it shows is possible? The only reason I could think of it changing is because of a power plan setting. Is there any power management software installed, or have you changed the Windows power plan settings?

[user1321466]

@DrZoo I think it was 28 because it works very fast. I did not have any soft installed. I changed power saving mode to "high performance" in windows, but it didn't help. Also as you can see core speed is only 399 but it should be 2.3GH

[DrZoo]

Well, I did a bit of Googling and found this. It could be something you could try to look into. When you took the picture of it being at 400 MHz, were you doing anything to try and stress the laptop or was it idling? Have you noticed it running hot or anything?

[user1321466]

@DrZoo Thank you for help. no it does not run hot. I tried cpu-z and geekbench, on both it shows very slow performance(8x slower compering to similar cpu-s)

[DrZoo]

In the new screenshot you added, uncheck BD PROCHOT and see if that changes anything. Although I’m not sure if that’s a good permanent fix

[Ramhound]

You can’t; You don’t have a CPU that allows you to chnage the multiplayer nor do you have a motherboard that would have firmware that supported doing so even if you did

[user1321466]

@DrZoo Thank you very much. It fix problem, now I can see in cpu-z that multiplier is 28. but I think I need to understand what does that flag do. you can put it as an answer I will accept it.

[Ramhound]

“Also do you know why it have changed from 28 to 4.“ The program in the first screenshot is the cause. You basically thermally throttled your cpu even though you didn’t need to

[user1321466]

Do you mean "OBSIDIAN" ? If yes - I installed it after I had that problem. So it cannot be the cause of problem

[user3692159]

Same happened with me. In my case cpu was stuck with maximum frequency of 0.75 GHz. I hibernated/fast shutdown my laptop and some how that restriction went away.

[user1321466]

well I don't want to overclock. I just want it to run in normal performance. At first it was super fast- but then I start work very slow. I don't know why.

[Ramhound]

Your question made none of that clear.

[user1321466]

@Ramhound unchecking "BD PROCHOT" fix the problem, do you know what does that flag means? Is this safe ?

[Ramhound]

Of course it’s safe. Submit an answer to your question. Google search indicates what it stands for.

[Christopher Hostage]

@user1321466 please create an answer to your question with your successful resolution, and links to your research with what "BD PROCHOT" means.

[Christopher Hostage]

By "overclock" I meant "change the speed or multiplier of CPU or memory", which appears to have happened. I thought that the -U series chips couldn't have their multipliers changed, but it looks like you were able to do it.

[user1321466]

I will create answer now. Thank you all for help.

[Ramhound]

@ChristopherHostage It appears the cpu was throttling itself

[DrZoo]

Oops sorry, I didn't refresh the page to see that you made an answer. You can read what I wrote and I'll remove it once you've read it.

[user1321466]

No need to delete your answer , I accepted it. thank you