Hello all i am having a problem where my pc updated and now only 2 of my 3 screens work(get a signal) my card is an Amd amd radeon 7900 series
Without the information requested by kingfish it is difficult to help answer your post.
But found this old Thread from Techpowerup concerning a HD7950 not working with three monitors. Three monitors on an ATI Radeon 7950 | TechPowerUp Forums
How are you physically connecting all three monitors to the GPU card you have installed? plus your computer hardware and software & OS installed.