Why does Linux heat up my computer?

I'm running Arch Linux, and this is what I do to reduce heat emissions.

1. I use laptop-mode-tools to control CPU frequency scaling and spinning down of the hard disk. The hard disk can heat up quite a bit if you keep it running continuously. But take note, spinning down of the hard disk too often will cause it to break. Desktop hard drives are usually rated for only 40,000-50,000 spinups. Laptop hard drives are usually rated for around 300,000 spinups. Link.

2. I installed acpi_call Visit here or follow this post for instructions to disable/ activate your discrete card . For me, I disabled the discrete card and only make use of the integrated card.

3. If you are using i915 drivers for your intel card, this will work. Check your output of lspci -mvknn | grep -B8 i915. If it returns non-empty, then you may add i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1 to your boot parameters.

   pcie_aspm=force can also be added if all PCIe hardware on the system supports Active State Power Management.

I use steps to mainly to reduce power consumption, but I also noticed a drop in temperature of more than 10°C as a side effect. I guess with less power used, less heat is emitted.