If the step-up is not possible you can try return your card and get a refund. Here in Finland atleast one store accepts 970 cards back and gives you a full refund. I have a friend who returned 3 months old Asus GTX 970 Strix and got a FULL refund. 
 
Evgas customer support works very well and they answer very fast. You should open new support ticket and make same question straight to them . 

BioHazardSperm
i honestly dont think the .5gb is going to solve your issue with the settings your pushing .That said what are the surrounding parts using this 970 ?

actually, i know it would.
 
i did a little more testing last night (this is WoW, btw, so not a super-demanding game) and when i was in an area that decreased the amount of VRAM beig used below the 3.5GB limit, it went back to 60+ fps, no problem.  so i know the card and my system are powerful enough to run these settings, i just need that extra little bit of VRAM.  as i said, i was getting a maximum of a little over 3.7GB of VRAM being used at that resolution and AA settings, which is still 200MB - 300MB under the 4GB total.  it runs fine up until the point i hit 3.5GB of VRAM, but as soon as it goes over that mark, slideshow city around 4 - 7 fps because of that idiotic 1/5 speed VRAM section.
 
System:
ASRock Fatality Z68 Professional Gen3
Intel Core i7-2600K @ 4Ghz (40x100)
XIGMATEK Gaia SD1283 CPU Cooler
16GB (4x 4GB) G.Skill F3-14900CL9-4GBXL DDR3 RAM
eVGA GeForce GTX 970 (04G-P4-3975-KR)
BenQ XL2410T 24"
SAMSUNG 840 Pro Series MZ-7PD256BW 256GB SSD
Coolermaster CM Stacker STC-T01-UW
eVGA SuperNOVA 1000 G2 PSU
 
i mean, GDI nVidia....WHY did you think running 512MB of the VRAM at 1/5 speed was going to be a good idea?  you should really be ashamed of yourselves for this....especially considering eVGA is coming out with a GTX 960!!!!!!! which can utilize the FULLLLLLLL 4GB at FULL SPEED!!!!!

stumbled across this guy with a better cpu running 4x with a 970 ,

none of that other stuff matters.
i already stated that things run buttery smooth with DSR at 4x and SSAA 2x + CMAA anti-aliasing when i am not in an area with a lot of people, which pushes the VRAM past 3.5GB.  when i saw the slowdown, i was at a little over 3.7GB of VRAM usage....anything below 3.5 = no problem.  this is very clearly an issue with the card and its VRAM partitioning.
 
my system and the GPU are plenty powerful enough to run those settings....otherwise, it would run like a slideshow every single time i run those settings.  i just need access to a full 4GB of full-speed VRAM.
 
i bought this video card back on Jan 2 before it was really well known about the VRAM problems (and certainly long before i knew about it), thinking that hey, this has 4GB of VRAM just like the GTX 980......i was on the fence already between the 970 & 980, and almost pulled the trigger on the 980, but changed my mind at the last minute.  huge mistake.
 
anyway, after speakin with eVGA customer service, they recommended that i contact Newegg about a return, since eVGA won't offer a factory overclocked GTX 980 in the step up program.  i did, and they approved a return for store credit, even though it was past the return period (probably being a Newegg Premier member helped a lot with that decision)....so i'll be getting a refund on my card and actually getting the factory OC'ed card i wanted from the start, so all my problems should be resolved soon.