I had just bought an AMD athlon x4 845, since it'd be quad core, and I could use it with my fm2 socket motherboard, I installed it and everything, but nothing comes up on the screen. Nothing. Fans running, power button on but no picture.
The board may need the BIOS updated. Here is the CPU support list for that board and the required BIOS version (or later) needed for the CPU to be recognized. Version 3.1 of that board Version 3.0 of that board
The board may need the BIOS updated. Here is the CPU support list for that board and the required BIOS version (or later) needed for the CPU to be recognized. Version 3.1 of that board Version 3.0 of that board
am I able to reinstall my other amd a6-5400k and update the bios, then replace the 845 and it should work right??
Yes. In fact that is the only way you can update the BIOS. But first be sure the links to the boards I posted above are actually your board. And choose the correct board version. We don't want to make any mistakes updating the BIOS.
Note: Once you re-install the A6-5400K, check what BIOS version is actually installed now. If it is a late version that is OK for the Athlon X4 845, there may be something else wrong.
And let me know which of those motherboard versions is yours.