I can't find any info on the PSU, but it looks like it's not good quality from the pics and brief descriptions of it. It could be causing the problem if it's failing. Even if it's not failing it has the potential to cause damage to your system. I'd recommend looking at a replacement.
Regarding the bios, you will have to look at the mobo support page for the bios updates, and instructions on how to do it. Read carefully, and follow the instructions closely. Often there is no need to update the bios, unless something isn't working, and in this case to be sure, i'd suggest doing a bios upgrade.
you can get some info here :
https://www.gigabyte.com/Motherboard/GA-F2A55M-DS2-rev-30#support-dl