There is some bad news if you are running an older Intel Core processor. It appears that Intel chips made from 1997 up to SandyBridge has a flaw that allows hackers to install a rootkit into the low-level firmware of the actual processor. This means bad things. Even if you format and reinstall your operating system, the flaw is still present - even if you swap hard drives. This rootkit could be very destructive and while Intel is working on a patch, not all CPUs will be able to be patched. AMD processors may affected, but they could be affected as well.
Once installed, the rootkit could be used for destructive attacks like wiping the UEFI (Unified Extensible Firmware Interface) the modern BIOS or even to re-infect the OS after a clean install. Protection features like Secure Boot wouldn't help, because they, too rely on the SMM to be secure.