Honestly and this is just my opinion but i can't stomach the poor single threaded performance of the bulldozer architecture. I do think you could get away with 300$ for i5-3570k/mobo combo, maybe a little over. Just throwing that out there.
As for the card i really like the 7970 drivers keep improving performance and if you manage to get a good overclocker bump it to ghz speeds or higher and you have much more value per $. That being said i have no idea which ones are voltage locked or not and it seems to me (others will disagree) that the 7970 QC is just all over the place. I had to RMA mine which it's XFX so that could've been the problem from the get go. I've never had to RMA anything before up until now, i guess it's part of the business though. Despite all my worries and concerns i still say 7970 just because at stock it's a good niche above the 670 and trades blows with the 680, and clocked up a minor 75mhz it's ahead of the 680 roughly.
Oh here is a 7970ghz edition (Gigabyte) for 430$ seemed like a pretty cheap price considering it's Ghz edition. Stock clock is supposedly 1100mhz according to newegg which would be stellar performance for the money.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125439Edited by Blackops_2 - 2/19/13 at 8:04pm