So my trusty 2GB GTX670 was golden when it came to games like BF4, Crisis, Skyrim with ENB, and other visually pleasing games, but when I heard about P3D and bought it , not so much. I had to have it, since I've been playing flight sims since I can remember, and and I stopped playing FSX because it frustrated me with the software, hardware limitations, and unpredictable CTDs.

My 670 runs great with default settings, everything on max(maybe autogen a level down), with no AI traffic, but craps out when I started to go crazy with addons, and I like my addons.

Over time, I bought REX4 Texture Direct, Orbx Global & Vectors, and I got MyTraffic to work in P3D after using a migrator. At KATL on the ground with max settings, overcast, and traffic on 80%, I get about 20fps with spikes maybe hitting 30, and honestly, if I didn't have the FPS counter up, I wouldn't even know it was under 32 because it still runs smooth. It's not until I start flying and looking around, and flying thru clouds, that I can defiantly start to feel a performance drop, as expected. Once I get above about FL250, frames smooth out to max. There's no doubt in my mind I need to upgrade my video card, and I knew I wasn't future proof with a 670, was just a matter of time. Using GPU-Z, my Core load is at 99% and my VRAM is maxed when actually flying, with addons.

I was looking at new cards, specially, the gtx780ti, or a gtx970. When it comes to performance, the 970 seems to bring higher clock speed, memory, turbo clock, higher pixel rate, and more render processors. The 780ti brings better float point, texture mapping, and a wider bus, and is more expensive then the 970. I did some searching, and found that it seems for alot of P3D users with addons, 3GB VRAM with the 780ti doesn't cover it, and it seems I'll need 4GB. Is this true? Which card should I get? Is there any other suggestions people have for a new card? I don't want to spend any more than $500, and I don't want a SLI setup.

TL;DR : I'm looking between a gtx780ti and a gtx970 for my new card to upgrade from a gtx670. Which one should I get? Any other suggestions for cards?

I'd probably get the 970... Newer tech being the main reason.

Greetings, I was in the same situation you are in.  I'm an SLI guy and forever loved my Gigabyte Windforce OC'd 670s, they were beast.  And getting into this sim really changed that.  Well, this and Star Citizen.  I actually opted for the MSI Gaming edition GTX 980s, and with them overclocked (Yes, only using one card for p3d but for everything else SLI applies) I'm quite happy.  In case you haven't heard, when you get your new card/s you should delete the contents of the shader folder and recompile them for your new cards.  I was quite disappointed when I just popped in these new cards and destroyed every other game and then saw no improvement at all in p3d.  The shader trick fixed that

However, after the shader trick, I have literally every slider maxed out with the obvious exception of traffic.  I agree with your assessment that 20-25fps can seem smooth depending on how stutter-iffic it is.  I have all FTX regions installed many of their NA airports, and some resource-hog Carenado planes, and with all graphics/lighting/shadow tick box/water reflections/ MAXED OUT I am getting about 20-25fps flying over PDX or and Seattle, and that is with road traffic at 15%, both water traffics set to 75%, airliner traffic 15%, and general aviation at 50%.  Any other time out in the wilderness and sight-seeing the frames are between 35-50fps which seems truly unreal coming from the 25-30 range.  This is running the game on a 2560x1600 native res Dell monitor and using the DSR trick to bump it up to 3620 x 2263 with MSAA x8 and Anisotropic Filtering set to 16.  Also with my cards I have my CPU OC'd to 4.4Ghz so I think that may help.  Anyways, I almost got the 970s because of how fond I am/was of my 670s, but ultimately decided on the MSI Gaming edition 980s and am blown away by how fast and QUIET they are.  Did you hear me?!  I SAID THEY ARE QUIET!!!  

 

Hopefully you enjoy whatever you end up purchasing, and happy simming to you.