It is very lilkely you will have issues. The 12 volt rail only supplies 16 amps. The 4890 is a 190 watt(peak) card. 190 watt /12 volts = 16 amps With capacitor aging taken into account I doubt you can run this card with that PSU, well at least not without random crashes now and then when power demand peaks.
http://www.kupujemprodajem.com/prodajem-novo-napajane-ms-PRO-550atx-p4-1232389-oglas.htm