What pc specs will beat the ps4/xbox 720 specs in terms of graphics performance?

An average modern gaming computer, the specs you listed will be as good as the new consoles HOWEVER it will not play games in 2-3 years time on max settings. A lot of games that are on both console and PC look a lot better on PC. So just because a game is on a console and your PC is as good or a better spec than a console doesnt mean you can buy it and play it maxed out. So you have to ask yourself how much can you spend against how important are cutting edge graphics to you. If you want t be able to play anything in another 2-3 years you'll have to pay more. Something like this:

Intel I5 3570k

8 gig of ram

Radeon HD 7950 or 7970 if you can stretch.

EDIT - Even then there is no guarantee, for example in one month the new Intel Haswell chips are coming out, might be worth waiting for them, even if you're not interested in paying the extra for them they should bring the cost of the current 3rd generation chips down.

*hypothesis* The PS4 has not been released besides the incontrovertible fact that that's in line with a 7850 and an A10 8 center CPU which would be under clocked (use much less potential and lose overall performance) yet all video games would be optimised to hell for it after the 1st 365 days or so and this could MILK overall performance from a device truthfully much less useful than another structures, I reckon that your build won't play video games as properly by using fact the PS4 even no count number if that's greater useful. TBH the two await a PS4 to return out or purchase crucial workstation (i5 + 7850 or 660 +8GB or greater RAM). Optimisations are each thing so even although your workstation will probable be a matching spec to the PS4 (overall performance clever) the video games will run greater suitable on the PS4!

the new consoles both have AMD HD 7790s

your PC will be fine for a few years.