Question MSI Motherboard error, not sure whats the issue

[uranic]

Hello! For some weeks now ive been trying to troubleshoot my Finacés PC without any luck.

When you try to boot the PC, it just goes directly to a black screen, it says either C5 or A2 in the bottom right corner, and it doesnt go further.

Ive removed one of the ram sticks, and tried them alone, done this with both, nothing changes.
Ive also tried to remove one of the hardrives, same there, nothing changes.
Same goes for the GPU.
The strange this is, it suddenly starts working, and this doesnt happen until the pc either reboots or crashes.
But now ive tried to start it without any luck for half the day.

the motherboard is
MSI h77ma-g43

Any suggestions to what might be the problem here?

 

[kerberos_20]

C5 is in BDS bios section (boot device selection)
A2 is related to storage device
from both codes i can tell that you have problem with storage drive

 

[uranic]

C5 is in BDS bios section (boot device selection)
A2 is related to storage device
from both codes i can tell that you have problem with storage drive

Thank you for the quick answer.
I tried to unplug both her harddrives and swap it out with one of mine. It worked but didnt since there wasnt windows installed it got the "insert boot media" or whatever its called page. so i got my drive with windows on and now its back to saying C5 in the corner. Strange.