I am looking to get a new video card somewhere along the lines of a GeForce GTX285. As I understand it this required a combined current rating of 42A or more.
Currently I am using an OCZ GameXStream 700w, which says it had a combined rating of up to 50a.
Does this mean that I should be able to run the GTX285 with out needing a new power supply?
I am a bit confused as to how the whole combined amp current works and how that translates to what I have available on my PSU. I know my CPU requires a 12v connector as well, so does this mean I have to account for some amount of drain on a total of 50a?
Yes, the Radeon HD5850 is a better option. Anyway, if you can wait a little (less than a month), as soon as the new nVidia cards (480 and 470) are in the shop, I hope the price of the ATI´s cards will drop a few bucks.
All of the power ratings listed for GPUs are for the system as a whole. They generally test worst case scenario using a top of the line core 2 quad extreme edition CPU with a massive power draw. A general rule of thumb, a good 550W PSU with ~40A on its 12V rail will run any card, a good 750W PSU with ~60A on its 12V rail will run any dual card setup or a dual GPU card.
While the GXS 700W isnt great for a 700W unit, its more than enough for any single GPU graphics card.
I also agree with going for the 5850, its a bit cheaper some places, uses less power, and therefore generates less heat, i wouldnt necessarily wait for the GTX470 though as thats over a week away and unlikely to be any cheaper, nVidia has a habit of higher pricing than ATI.