So my XFX HD 4890 finally died on me. It having a lifetime warranty it is being replaced with the equivalent 7770. My question is should I buy another 7770 and crossfire? Would I notice whole lot difference, performance-wise? I currently have a PII X4 925e OCed to 3.26Ghz, 8GB DDR2. I plan on upgrading to a FX-6300 and 16GB DDR3. Of course I'll have to get a new mobo.