Aurora R4 lost factory overclocking after bios update

Hello, I have an Aurora R4 built late 2011. When purchased I payed the extra money to have it overclocked from 3.9 to 4.2. i did a bios update awhile back,  i had taken a break from gaming for awhile so just regular use of the computer i didn't really notice, but once i started gaming again i found it was not what it used to be. i started checking system settings to see what it was running at and found its back down at the 3.9. i was told by a friend that if you do a bios update you lose the overclocking. How do i get it back?? Ive seen a few different things on you tube but i'm not willing to start guessing and fry my pc. so i wanted to ask you guys. i feel if i paid for it in the first place i deserve to keep it even after doing an update. hopefully someone can help!

Thanks,

Kate