# What's causing BD PROCHOT to be constantly red and what is IA PROCHOT? My CPU is limited to 0.8ghz, how to fix this?



## hellpal (Nov 29, 2021)

So as the title mentions, BD PROCHOT is constantly red. I am running bootcamp on a mac, but the cpu is limit is there on the Mac side as well. What could be causing this?

I also ran HWINFO and it says IA PROCHOT Current/Minimum/Maximum as Yes/Yes/Yes respectively. What does this mean?

Also what are the DIMM temperatures listed and why are they so high? Although I did notice these were around the same temps before this issue came up. However I don't know if the IA PROCHOT was like that. I didn't have any BD PROCHOT issues in throttlestop until now. I would initially have pl1 and pl2 along with current as yellow after starting up TS. After clearing it doesn't popup again even after gaming and such.

Disabling BD PROCHOT in TS does remove the throttle on the CPU but I am somewhat worried about doing that without making sure that it'll be okay and understanding what's causing it. Also then there is the issue that I have the issue persisting after booting into Mac OS as well.

Edit: Added log file as well, while BD PROCHOT is on and with it disabled through TS.


----------



## unclewebb (Nov 30, 2021)

hellpal said:


> BD PROCHOT is constantly red


This is a common problem for many different laptops and some desktop motherboards too. Many different MSI desktop boards have this issue.

Your log file shows that your CPU temperature is fine. BD PROCHOT throttling is happening when the CPU is lightly loaded so most likely, this is a sensor of some sort that has failed. I have never come across any publicly available documentation that shows what sensors are being used on any individual laptop. When a sensor dies or shorts out, it will send a throttling signal directly to the CPU using the BD (bi-directional) PROCHOT signal path. Disabling BD PROCHOT blocks these throttling messages from getting to the CPU.

Disabling BD PROCHOT does not interfere with CPU thermal throttling. If the CPU ever gets too hot, it will thermal throttle to protect itself whether BD PROCHOT is enabled or disabled. PROCHOT (processor hot) and BD PROCHOT are two different things.

It is fairly easy to disable BD PROCHOT when running Linux but I have no idea if this is possible when running the Mac OS. You need direct access to read and write information to registers within the CPU. To disable BD PROCHOT, you need to disable bit[0] of MSR 0x1FC



hellpal said:


> I also ran HWINFO and it says IA PROCHOT Current/Minimum/Maximum as Yes/Yes/Yes respectively. What does this mean?


Some monitoring software does not report BD PROCHOT throttling 100% correctly. You can trust what ThrottleStop is telling you. Do not run HWiNFO when using Limit Reasons in ThrottleStop. 



hellpal said:


> DIMM temperatures


It is possible that the DIMM temperatures being reported are not accurate. The developer of HWiNFO may not have done any testing while running Boot Camp on a Mac. If those temps are accurate, they look terrible but I do not know what you can do about that. If you are not having any memory errors then I would not worry about the HWiNFO reported DIMM temperatures.


----------



## Cromanin (Dec 1, 2021)

Unclewebb,

what are your thoughts about future availability of manipulation with BDPh / Ph registers? Won’t manufacturers / MS / Intel disable it like they did voltage control?

I have Lenovo Tiny desktop that constantly triggers BDPh plus their engineers were lazy enough to set Ph at 85 instead of working on proper cooling. So TS is the only thing keeping that PC operational. Don’t wanna update one day and find it effectively useless.


----------



## hellpal (Dec 9, 2021)

unclewebb said:


> This is a common problem for many different laptops and some desktop motherboards too. Many different MSI desktop boards have this issue.
> 
> Your log file shows that your CPU temperature is fine. BD PROCHOT throttling is happening when the CPU is lightly loaded so most likely, this is a sensor of some sort that has failed. I have never come across any publicly available documentation that shows what sensors are being used on any individual laptop. When a sensor dies or shorts out, it will send a throttling signal directly to the CPU using the BD (bi-directional) PROCHOT signal path. Disabling BD PROCHOT blocks these throttling messages from getting to the CPU.
> 
> ...



Hey unclewebb, sorry for the late response! Thank you for your response it gave me new knowledge to keep in mind. Fortunately, the cause of the BD PROCHOT throttling was found. It was the battery causing it. Well since the battery has degraded and apple doesn't want the laptop shutting off due to lack of power to function at full capacity when demanded (such as turboboosting), they have made it so that a BD PROCHOT signal is constantly sent to limit the performance of the laptop. I replaced my battery and now performance is back to normal. Hope this helps someone! I had this issue on a Macbook Pro late 2013 15 inch retina model.


----------

