As I understand it, it's also the CPU manufacturers, motherboard suppliers, and system integrators. Intel and AMD are not consistently supporting S3, and some m

As I understand it, it's also the CPU manufacturers, motherboard suppliers, and system integrators. Intel and AMD are not consistently supporting S3, and some motherboards (iirc) toggle it off even when the chip purports to support it. System integrators may also leave the BIOS setting for S3 off even when supported. As for why? As many know from the history of Linux support for sleep, it's not always been great. Every device in the system has to support it, and there's a risk of corrupting state when execution resumes. It's much easier to keep the system running in a lower power mode. That's true of all of the device drivers and firmware on the system too. It's frankly shoddy work though that it works so poorly that the order in which one unplugs their laptop and closes the screen affects whether it correctly enters S0ix. I can't believe issues like that have made it out of QA on laptops over and over again, resulting in laptops overheating and reaching 0% charge. The Linus Tech Tips video here goes into the details: https://www.youtube.com/watch?v=OHKKcd3sx2c https://www.youtube.com/watch?v=OHKKcd3sx2c