Here is X58 running the Xeon .. this will show you how different gpu's scale under the platform..
HD 7950
Graphics Score
8 343
I scored 7 664 in Fire Strike
R9 290X
Graphics Score
12 573
I scored 10 978 in Fire Strike
If I had to guess, I would say those scores are right in line with what a 5820k would score - nice overclock!