beegeepee :
So, should I get more than 550W. I liked Looniam's suggestion:
"you can drop 100 watts off of each PSU; a 650 for the 7970 and a 550 for the 670 set up.
(pssst i am a fan of XFX being made by seasonic)
XFX 550W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply
$59.99 -$10.00 +FREE s/h $49.99"
particularly because it is cheaper. But do you think I will pigeon hole myself if I go to that low?
one thing is those PSUs, the XFX 550 i suggested and the 650 you have on the first build that can move to the second, are quite enough for overclocking the cpu.
also if you are not already setting aside money for a budget to go CF or SLI you will not in the near future; with the two different cards you choose (the 670 and 7970) it is doubtful you will have a need for anything better unless you get a multi monitor set up and even then both cards (esp, the 7970) will do well depending on the game.
with power saving features of cpus and gpus systems idle usage can be as low as ~100 - 150 watts; far below stressing out any quality 550 watt PSU. just keep in mind that systems spend more time idling then under full load. and since efficiency takes a big nose dive when less than a 20% load on a PSU getting too big of a PSU is a waste of money when it sits there idling with less than 74% efficiency.
on the other hand, if you have the budget to keep the PSUs you have then go for it. at least you are not insisting on getting a 950 watt PSU for a i3/7770 set up.