Hi , i a newbie when it comes to over clock, but i have increased the multipier to 21 just a very mild increase, now i have tried increasing the bus speed just mildy 133 to 145... i have not touch the voltatge. i want to know it is okay to increase bus speed without increasing voltage is it safe? i have 17 920 and noctua nh12? just wanna take it step by step. thanks.