about vram and new gtx 780

i guess you wont be able to lauch even PackMan 2016 on 780, so it is worthless. Go with the simple 780 one.

When comparing two cards which are identical except for the amount of VRAM, the card with more VRAM is a tiny bit slower until the smaller card's VRAM is full. It's due to having a larger address space to work with. But the difference is so small that only benchmarking will reveal it unless you're playing on sub-30 FPS.

That much VRAM is worthless if you won't be filling it. If 6GB of textures is commonplace 5-6 years from now, you'll see cheaper video cards available in 5-6 years with 6GB of VRAM. You'll likely spend less buying an appropriate card of today, plus an appropriate card of 5-6 years from now.

I would go for a card with 2GB of VRAM today. 5-6 years ago, 1GB was the most that you expected to need. Today, that's usually 2GB. But in 5-6 years, I'm expecting 3-4GB. 6GB will be for enthusiasts with a few of those 4K displays that are still expensive today, but may be cheaper in 5-6 years.

If you want to be able to run today's games at 1080p, 2GB is overkill. If you want to be able to run today's games at 1440p, 3GB is plenty. But note that as your resolution goes higher, the noticeable effect of post processing diminishes. It becomes less of a necessity, unless you're playing older games with simpler polygon models, but then there's very little improvement.

Betabot's suggestion is good, a 770 or 780 from ASUS or EVGA. Though I do like Gigabyte's Windforce and MSI's Twin Frozr cooling systems.

Check reviews and prices, but you would be very happy with a 770 for about 320 USD. It will have you playing 1440p and flying. Games which are optimized for Mantle (AMD) will not do as well for you, but you have superior PhysX and lower heat production and power usage. The 780 is your best bet if you want to not worry about an upgrade for more than 6 years, but I personally wouldn't go higher than the 760 today, since I don't feel that I need more than 1080p.

The Titan series is a boutique product. It says that you spent 50-100% more for 5% more performance. Same with AMD's 290x.

As for the Thief reboot, it has fps stability issues on every card. It is a badly optimized game. Seriously, go check out player reviews on Youtube.

imho: it's the slowest component of your system that sets the performance, not the fastest. The only sensible way to build a pc is to have it well balanced

Also consumer electronics, in particular pc components, don't fit too well into the idea of 'investment'. In order to get a card that will still perform well in 5 - 6 years time, you need to fork out a huge amount of money today, knowing that:

you will very unlikely use the full potential of the card today

in 3-4 years other components of your pc will have become the performance bottleneck anyway, so you won't be able to use the full video card potential then either, unless you upgrade the rest too. But there's no guarantee that today's standards will last that long

drivers updates for older cards are often disappointing, if existent at all

in 3 - 4 years time a middle-range, decently priced card will be way faster than the fastest card you could buy today

My recommendation: pick the most demanding game you plan to play TODAY (thief is not a good example, as others said it doesn't seem to be a well written/optimized game yet), find out what card would allow you to play it at highest settings AT YOUR MONITOR'S RESOLUTION, then pick a card that performs a bit better than that.

You will be able to play anything you like for a while, up to a couple of years, with top to good settings. Then when you feel like your system is too slow, upgrade the slowest component(s) (I'd bet it won't be the video card) or if needed consider a full system upgrade.

I see. Forgot about that. You don't want to be like that old Mac Pro with HD 4870 screaming like "just 1 more series!!!"

It's something similar to "GPU supports DX 11.2 API, Hardware Feature Level 11_0."
And look like there're 2 new hardware features already mentioned here.