problem Black Screen PROBLEM

[Darknorth]

OK, so i have a black screen problem and let me explain it, my PC is kinda old and i cant really afford to get a new one any time soon so i'm kinda stuck with it, the problem appeared yesterday when i suddenly got a black screen, my PC seems to be working fine in the background so i restarted it, upon restart i got all the usual stuff that comes before the windows boot and a split seconds after you see the win 10 boot icon appear the black screen strikes again, again all the things seem to be working properly in the background BUT i cant see anything, this happens every time i try to power on the PC, i tried out switching GPU's(have a spare one lying around and it kinda overheats) also swapped the RAM and tested it individually, i thought it might be the windows and i tried to go into BIOS before the windows boot cause it's there that the black screen appears but the second after i get into BIOS black screen strikes again so i'm left with 2 options, either something is wrong on the board or the monitor, or i missed something and it's something completely else, anyone encountered a problem like this before?

BTW the PC Config is;

GIGABYTE Motherboard (forgot the model cause it's so god damn old)

CPU: AMD Phenom 9600 AM2+ Socket 

GPU: Radeon 3870HD

HDD 320GB x2

RAM: 6GB DDR2

EDIT:

Yeah i think i found the problem to be the monitor, just tested it with my laptop which has a VGA port and the same thing happens when i try to boot the PC, have a picture for a split second and in the next one it's gone