It is compatible. Just check you PSU to make sure it can handle the graphics card, but in most cases it wont be able too so I would suggest upgrading the PSU. 500W should be enough, but dont buy a cheap unknown make.
Realistically the only that that will determine it is your PSU. I have the 4890 and it takes a 500W PSU which is above and beyond most standard PSU's from pre built computers. Check what the power supply is, but likely you will need a new PSU to support a 4890 or anything in that same power range.