Random blue screens of death (BSOD) are usually memory related,
I recommend you remove all of the memory and then try the machine with only one module installed at a time. If you have the Windows 7 installation media you can run the memory test routine from the setup menu against each module individually, and assuming no problem is found, again with all three modules installed.
If the memory checks good the next thing I would try is to replace the power supply. The capacity of the unit you have is probably adequate, but it may not be delivering rated output for some reason.
Luiz_Fileto, I was checking the power supply you are using and the minimum recommended power supply for this motherboard is 460 W.
I would recommend you perform some basic troubleshooting in order to find out what is causing the BSOD, but it will be a good idea to change the power supply for a bigger one.
- Test the system out of the chassis, minimal configuration please. (Motherboard, processor, power supply) No memory. It should give you 3 beeps.
- Add 1 memory stick on DIMM #1.
- Remove the CMOS battery and leave the system without it for about an hour. Then put it back on and restart the system. Desktop Boards — Troubleshooting BIOS issues
-Test a different a different memory stick on DIMM #1.
If you are able to access the BIOS, please check which BIOS version is installed. Check if you need to update it.