I have a 13" Sony Vaio laptop (model SVS13A1C5E) and I upgraded it to Windows 8 with a fresh install, after upgrading I installed Win8 drivers listed here.
Now I have a problem with the CPU usage (it drains my battery), in Task Manager I can see that the "system" process is always using 15-20% of my CPU (i7-3520M) and looks like the usage is on a single core. This is what I found by using Process Explorer, the usage comes from ACPI.sys which looks like it is generating a lot of hardware interrupts.
By doing some research I found out that should be an issue with some drivers but I don't know how to figure out which one is causing this. (Please do not tell me to "upgrade" to Windows 7)