I am currently working on my first PC build and my dad made a comment on something that I noticed too. When I accessed the BIOS menu I went to the Temps page and I saw that my CPU was at 30 degrees Celsius, as I was checking a few things I went back to the temps page and saw that my CPU temp was climbing and I was not putting any load on it. I am just wondering if the CPU fan (stock that came with the processor for now) is not mounted all the way or if this is normal.
what I have so far (Work in Progress):
Asus P8Z77-V LE
Intel i5 3570k
Thermaltake 750W power supply.
Your temps are fine for an idle load. The CPU heating up in the BIOS is most likely due to the fact that the metal of the heatsink was ambient temp when you turned it on, and is being heated by the CPU, meaning that youv lost the small benefit of cool metal against the CPU.
Also would hardly call a 3°C change over 10mins a "spike" in temperature . Your gonna have a heart attack when you stress test the machine and see it spike from 30°C to about 55°C in a few seconds.