Then if I got a normal PSU with high watt isit possible to
change it into
crossfire ready? Instead of buying a new one?
Because I used some watt caculator online and they stat I aleast
need 750w :( if I decided to use 2 gpc..
So lets say if I used the GX Series GX-650w then how am I going
to hook up 2 by 2nd gpc? If its not crossfire ready?
At least 750W but that's only minimum requirement. To have
continuous and realiable stability a higher capacity preferred.
My advise for you is not to cross the bridge until you come to
it. 
Since you have reasonable graphic card, you may well proceed on
to use it with your newly rigged system using the recommended PSU
until such time where you got no choice but to upgrade. When the
time comes, I believed you may have enough savings to upgrade
further. Who knows, you could have two systems by then.
For computer enthusiasts, you must willing to accept that
there's no such thing as permanent or long lasting configuration
that could be relevant to the ever changing development in the
industry. One thing in life that is constant is change. So we might
be using xfire/sli now but who knows there will be future
configurations better and less headache than that. Probably in the
upcoming pc show, you'll never know.
As for question on the GX Series, it is SLI-ready not much of
Xfire. But it's not about connectivity, it's about the flexibility
of power distribution whilst on demand. The difference in usage
between SLI and Xfire is as described in the earlier article.
My question to you is how soon you want to use 2 graphic cards?
If it's not that soon then you could purchase other brand of PSU
that comply to your current configuration and start rigging.
Leave the flexibility in power capacity for SLI/Xfire to the
next time you would upgrade.
You could always sell away your purchased PSU via local online
classified sites when you decide to upgrade to higher capacity.
Just keep the original packaging intact. There's always somebody
who seek for best deal in used hardware.
Hope this helps.
