The tall thin heatsink at the edge of the motherboard is cooling part of the VRM. The VRM or Voltage Regulator Module is responsible for converting the 12V input down to 1.3V or so for the CPU. Under that heatsink there are 2 of the 8 phases for CPU Vcore and 2 phases for Vsoc. It would be pretty safe to remove that heatsink, even in a passive case because:
- Vsoc draws very little power, especially with no iGPU.
- The VRM is designed to survive providing 200A to a 16 core 3950X, 50A to a 2600 is very easy by comparison. Maybe 6W of heat split among the 8 phases so <2W of heat on these 2 phases.
- The MOSFETs will happily run all day at up to 125C.
- The MOSFETs are smart power stages which communicate their temperature to the controller, and have many built-in protections, so there's extremely little risk of damage. The controller probably shares load amongst the phases based on temperature but I can't find a datasheet to confirm.
Yup, most MOSFETs will have no trouble running at 125C! The power supplies in some of our products occasionally run at 180C, without heat-sinking. But these aren't designed to last as long as a motherboard VRM.
In general cooler is better. At high temps you'll see temperature related aging accelerate (e.g. solder, PCB substrate, electromigration in the parts), but you'd probably be okay. The PC would become obsolete way before the VRM fails. The worst case I can imagine is the MOSFETs and inductors heat up, bringing the local temperature up to a point where the controller IC enters over-temperature shutdown, but it's unlikely.
Personally, if the current heatsink is too big I would just find smaller ones and attach them. I don't really have a good reason, I just like parts running cool :)
Thank you so much for the explanation. How do you know all that? I am interested in learning about motherboard design and wonder if there are books you would recommend about it.
I'm an electrical engineer by trade. The specifics in the post were lifted from the linked video since he already did the hard work of looking up the components and calculating the efficiency curve.
I wish I had a book to recommend about motherboards specifically, I would like to read it!
- Vsoc draws very little power, especially with no iGPU.
- The VRM is designed to survive providing 200A to a 16 core 3950X, 50A to a 2600 is very easy by comparison. Maybe 6W of heat split among the 8 phases so <2W of heat on these 2 phases.
- The MOSFETs will happily run all day at up to 125C.
- The MOSFETs are smart power stages which communicate their temperature to the controller, and have many built-in protections, so there's extremely little risk of damage. The controller probably shares load amongst the phases based on temperature but I can't find a datasheet to confirm.
Ref: https://www.youtube.com/watch?v=yXwjwxb39EA