Hello. I have a very old system with 2500k and a msi p67 motherboard. I've never done an OC before so I tried to start with a minor one by going up to 4.2 Ghz. My system is stable (temps are between 30-35C on idle and 50 at load) but the cpu won't ever go down below 3.50 ghz on idle. I literally only changed the multipler in bios, didn't even change the voltage or any other value. If I go back to stock clocks, it idles down as normal but not with this setup. Is there any additional thing I need to do?