GPU fan spinning, no image on monitor

hyddenblue

Honorable
Sep 24, 2013
4
0
10,510
I bought a Radeon HD 6850 to replace my 8400 GS and after switching them and trying to start the PC my monitor just shows a black screen, but the fan on the 6850 is spinning. GPU not detected in device manager or AIDA 64.
My components:

PSU - Generic 450W
CPU - Athlon II X2 250
RAM - 2GB DDR2
GPU - Radeon HD 6850
AIDA 64 says my motherboard is MSI NF725GTM-P31 (MS-7309)

I have a VGA monitor so I used a DVI to VGA adaptor, after I got the black screen I switched to my onboard graphics and I noticed that my PC successfully booted into Windows. Also my PSU doesn't have a 6-pin by itself so I bought a molex to 6-pin cable as well.
I know my stuff is old but I wanted a GPU first to play some newer games until I can upgrade the rest.