OK what is that machine used for most? Heavily multi threaded stuff where 6 core will help you out just as much as the 4770Ks fast single cores. Is it basically a gaming machine? or iis it a little of both at the same time ETC.
If you need 6 cores I found a i7-970 for $353.00 from Starmicron I have dealt with them in the past 3 times and they have quick delivery. Seems to be the best place to get older CPUs at pretty good prices. Here is the link http://starmicroinc.net/intel-core-32gh
A 130 watt 6 core 32nm chip with a 3.2ghz base with a 3.46 turbo plus you can overclock it to 4.0 to 4.6ghz Your mileage will vary:) Those 970s where released at $595 if i recall correctly. Also you will need a good cooler if you want to get over 4.1 ghz if the chip has it in it. At 4.1 ghz with the big intel tower cooler it hit over 85c in the review i read.
Its up to you If you want 6 slower cores for 385$ That can be overclocked mind you " to what level thats a big ?? bur 4.0 ghz should be possible" A 6 stock 3.2ghz core i7 970 scores CINEBENCH at around 8.0 points. At 4600mhz it scores 11.33 points. A stock 3.5ghz 3770k is 7.6points , 3.5ghz 4770k 8.15 points. But my overclocked 2600k will hit over 9 points depending on how high my overclock is. But since I have had it for over 2 years I do not have any reason to run 1.5 volts to get 5.1ghz at this point. "Unless a 240mm AIO cooling system somehow gets added to it" I am running a single 120mm push pull Asetek h50 style AIO water cooler on it now and with my right now 30 degree ambient temps in my hot computer room "summer" @4.6ghz @1.368volts Idle my hottest core is core #1 37c coolest is core #0 at 34c, running prime 95 for 5 minutes my hottest core always core #1 is at 70-71c with my coolest core #0 is at 66-67c
The only reason i added my 2600k overclock score is because the 3770k and 4770k overclock well also.....But run SO SO much hotter unless you go into delidding to replace the tim between the IHS and CPU die but thats a conversation for another time.
So the choice is all yours, for $385 bucks just to drop in a CPU for 2 more cores and a possible good overclock to make up for the single core performance. Or keep your rig and build a new up to date one for a lot more then $385 Also to need the extra performance to get the most out of you 670 sli setup will only matter when you are running at a low resolution or no AA or AF and going for sheer framerate plus a slight OC and 2 extra cores will help out If you are running NV surround with 3 monitors the CPU will not bottleneck 2 670s. But to be honest If you do have the money for it the 4770k cannot be beat for gaming with just a SLI setup. Now if you where running Tri or Quad SLI i would say go for sandy bridge -E or wait for Ivy bridge-E. Also with PCI-e 3.0 remember you get double the bandwidth of 2.0 Since no video card can really saturate a 2.0 x8 slot. You can get some new killer 1150 mother boards like the MSI z87-g65 or sat a ASrock Z87Formula board that will run tri SLI great since it will split up the top card to 8x and the 2nd and 3rd slot to 4x pci-e 3.0 using all the lanes from the CPU and not from any added PLX chip that adds latency. 4x at pci-e 3.0 equates to a 8x pci-e 2.0 slot. I really like the Asrock Formula boards they are well made top end boards that are a good bit cheaper then the other big name boards. They sorta fill the spot left by DFI motherboards since they went under or got bought out i forget which.
2600k@4660mhz CM Nepton40XL 16gb Ram 2x EVGA GTX770 4gb Classified cards in SLI@1280mhz Stock boost on a GAP67-UD4-B3, SBlaster Z powered by TX-850 PSU 2xHTPC's Both w/i3 2120's,1xasus LP HD6570@850core 1000 ddr3mem 1xHIS hd7750@1125core1400mem