Why is the fan blowing full speed, all the time?
I have this model as a secondary Mac laptop. It runs Mac OS X 10.11.6 reasonably well when I don't limit CPU power. Has received SSD (OWC Mercury) and RAM (Kingston) upgrades, as well as a new battery.
However, even with rather low CPU usage (15%), the fan is blowing full speed, all the time. Cleaned radiator? Check. Thermal paste? Check. Reset SMC and PRAM? Check.
CPU temperature is hovering around 65 degrees, MCP temperature is currently at 72degrees, but the CPU can be 10 full degrees cooler than the MCP. Even at full fan speed / low CPU usage, MCP temperature doesn't decrease very fast. There's no apparent relationship between CPU temperature and fan speed.
Even if it dramatically slows down the whole machine, I set Macs Fan Control to limit fan speed at 3800rpm as the noise at full speed is just unbearable, and just let it back on when I need more power. Interestingly, the fan speed issue also shows up under Mac OS X 10.6.8 (dual boot from the same SSD), so pretty sure it's not a software problem.
Some unanswered questions:
- Why is the MCP hotter than the CPU most of the time?
- On one forum, I read the MCP sensor can become faulty. But where can I find the schematic for this MacBook5,2 board? I was able to find ones for MacBookPro8,1, but nothing for MacBooks.
- As I last resort, I though about gutting out this laptop and making a series of small holes in the bottom case to help with cooling. I'm afraid this would in fact allow the computer to suck in even more dust. Is it a reliable solution on this model?
- And where would I need to drill to allow for maximum cool air intake without lettings the other components overheat or for the laptop to be even more vulnerable to liquid intake?