If one of your cores reports at 4.2, while the other three report as 3.8, it probably means the 4.2 is the currently active core, (Active Core Count = 1) while the other three are not being used at the moment. To get all 4 to always be at 4.2, you might have to "sync" all cores (if that is a bios option), but, the cpu will run hotter. Generally, on light loads, one core is active & handles the task while the other will be "parked" because they aren't needed. On heavier loads, 2, 3, or all 4 cores will engage. If your cpu has 4 individual cores, in most cases, one core is active, 3 are idle, & this helps keep cpu power consumption and cpu temperatures low. Ok? That's it in a nutshell. Any further look into what the cpu does, how its cores engage and handle tasks should be looked at using google searches, and overclocking guide books etc ... I don't oc, so my input ends here