Question Pc wont display anything after cpu upgrade

[Wayak69]

Recently bought a amd phenom x2 955 for motherboard asus m3a-h and after installing cpu everything works but no display signal.

 

[rgd1101]

full system spec? include brand and model of the psu

update the bios?

M3A-H/HDMI - Support

www.asus.com

 

[Wayak69]

Psu is fine because it was recently upgraded from 400w to 550w and was with my old cpu
Full spec
MB asus m3ah
Gpu hd 4870
Cpu phenom x4 955
8gb ram kingston
550w psu
Thinking its just the gpu cuz i bought it from aliexpress 😂