May be some help to those running a pair of these at 1440, just some observations from my 780's, similar grunt, less vram then a 970.
Desktop use:
The usual's open, chrome, thunderbird, steam, origin, GFE, logitech software running, vram usage was around 600mb at idle use.
Closed the majority and got vram idle usage to 220mb, chrome it appears likes to allocate 2-300mb.
Shadow Of Mordor:
Vram usage sat happily at 3000-3030mb constantly, no hitches in frame rate which sat at a constant 100fps using the follow settings, ultra for everything besides texture quality, lighting quality and ambient occlusion which were all set to high, motion blur set to FXAA+Camera. I have played this at 'full ultra' before, it looks no different what so ever.
What I will say is this game appears to cache as much to the memory as possible, I can see it raising in 300mb or so chunks as the game loads. This could be why 970 users are reporting stutter, as it may be trying to allocate over 3500mb. Should be fixable via drivers if needed.
Far Cry 4:
Ubisofts latest crap fest...I couldn't get the vram to peak above 3000mb without going nuts and using 8xmsaa. Things that appear to produce a strange stutter (similar to that on launch day FC3 with multi cards)...
AA levels, all levels of MSAA & TXAA make the game stutter without noticeable frame rate drops.
Ultra textures, the grunt is there, vram isn't hitting its limit, yet stutters, drop them down to 'very high' and the game becomes instantly smoother.
SSAO, I found the game smoother moving this over to HBAO+ (Surprisingly).
Conclusion so far: Check whats being used at desktop level, you'd be surprised. For SoM, tweak the texture and lighting settings especially, both are vram heavy, ultra textures carries a 6GB recommendation at 1080!! FC4, play with all of the settings, this game is seriously bugged in many areas, vram usage doesn't appear to be one of them. Some areas its seems to report only using a single maxed out CPU core too.
Would love to hear how some one with a pair of 970's fairs on those games with those settings and vram usage, I will try some other games as and when I get time.
Final thought for the evening, with background processes using 2-500mb, could nvidia configure the driver to move those process to use the slower 0.5gb bank?