Just thought I would chime in since my setup closely matches what op is considering.
My current setup is:
i5-4670k @ 4.2ghz
MSI GD65 z87 gaming mb
2x gtx770 msi oc sli
16gb corsair veng 1600mhz ram
CM 800 silent pro gold certified ps
Corsair h55 closed loop cpu cooler
180gb intel 520 SSD (OS and game cache using steammover)
128gb samsung 840 msata SSD (game cache)
2tb wd black (storage)
I have been playing bf4 beta since oct. 1 at 1920x1080 ultra settings and fps occasionally dips down into low 20s for a brief moment, I use vsync so otherwise very smooth. The drops are very brief, less than a second but have lasted a few steps, maybe 2-3 seconds in a series at most. Disabling msaa 4x does help performance slightly, but not much. I checked GPU usage with afterburner and this game is not really stressing my cards at all, temps are low 50s and usage was pretty consistent at about 60% on both cards. I understand vsync will limit GPU usage not drawing extra frames, but if the cards have headroom to spare there should not be slowdown unless cpu is bottle necking performance. I also checked cpu usage and it would peak at around 80% using intel overclocking utility to monitor, temps were consistent at around 60 degrees C with all cores running at 4.2ghz. I do not think this is indicative of final release performance and is to be expected with beta software. I am not using beta drivers as they gave me problems in far cry 3, I am using latest WHQL drivers, 220.49 I believe. This PC was purpose built in August for the upcoming games with bf4, titanfall, AC4, etc in mind so I kinda went overkill I know, but if wanted to get the best performance for the buck with minimal upgrades for years to come. So far I have I have not found a game I can not max or ultra with rock solid silky smooth performance at 60 frames with vsync on. It's everything I had hoped for, bf4 was the first game to give me (very slight) problems. Don't fret.
I am certain battlefield 4 will meet my lofty expectations and yours aswell, but for now the beta is very system intensive and most likely not optimized, otherwise it would be final already.
My .02
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