I understand that, but iirc people with the same computer (Dell XPS 8300), have had successful results from popping in, say a 560ti. Considering they both have the same power requirements, I don't see the problem.
Shouldn't the main thing be the amps on the 12V rail?
I'm not looking to replace my power supply, just a better card than I have right now. I have a budget of $100 dollars or so.
My cousin had upgraded his HD4870 to a GTX670, so he just has it lying around.
With that being said, would it be more cost effective to just replace the power supply and pop in the 4870? (And get decent performance)
A free 4870 is a great deal. Just try it out with your existing power supply. If it doesn't work, we'll recommend some good ones for you. Corsair, XFX, SeaSonic, Antek are good ones generally. You'll need about 500w.
From what I've read isn't it the 12v rail what really matters, rather than the wattage? Not to sound stupid, but how can I determinate the amps on the 12v rail?
I'd just like to make sure I have a decent chance at running the 4870 as the card is on its way.
Also, from what I've heard the power supply in the Dell XPS 8300 is of a high quality, so that should be a factor as well no?