I have a 

i7-3770k (not over clocked)

geforce 760 gtx sc 2G video card

8 gigs ram pc-1333 (?)

All the games you listed run on my computer. X-rebirth fps might go down to maybe 12 fps (?) but isn't really noticeable. I don't think a 4G card would help that much versus a 2G card. Far Cry 3 and those other games should run easily. You can ask in the steam community hardware discussion area. 

First of all, the amount of memory should most definitely NOT be your primary concern.  (Granted, the video memory requirements of games have been rising steeply of late, nevertheless, it is not one of the main performance bottlenecks.)  I really can't stress that enough, for some reason that seems to be the primary thing that card manufacturers use to advertise their cards, but it is comparatively unimportant.  What you really care about are things like clock speed, number of cores, and memory bandwidth, but with a few exceptions those are always expressed compactly by the model number.  With very few exceptions, higher model numbers are always performance improvements of (at minimum)somewhere around 10% in FPS of AAA games (that's speaking very roughly of course, but it's a good rule of thumb), so you pretty much only need to look at model numbers.

Next, if you can stretch it, the nVidia GTX970 is the best performance per unit value on the market right now by a VERY wide margin.  Granted, things might change drastically come spring when nVidia and AMD finally get their 20nm chips on the market.

It's almost always a good idea to buy video cards that are very near in price to the reference.  The main reason for this is that the primary thing which is done to augment cards is adding more video RAM, which is really not needed in most cases.  So, for example, I'm pretty sure the GTX960 reference model has 2GB of RAM, so I'd strongly recommend against buying one with 4GB for $50 more.  It just doesn't make any sense, you'd be better off saving the extra $100 to get the 970.  The reference 960 is probably pretty nice, judging by the 970 and 980, but I haven't looked at benchmarks myself.  I was in the market for a 980 a few months ago, and the 960 wasn't out yet.  

Here's a good review for the 970

http://www.guru3d.com/news-story/review-nvidia-geforce-gtx-970-and-980-reference.html

Of the games you listed, Far Cry 4 is far and away the most demanding.  Judging by the performance I get on things like Alien Isolation and Elite Dangerous, I have a feeling Ubisoft is partially to blame, but it is one of the best looking games I have seen to date, so it's not totally surprising.  I run it on a GTX980, which is for the time being the best factory-spec single GPU card on the market, and with the settings maxed out I only just barely maintain 60fps at 1080p.  Most of those other games could probably be very easily handled by pre-Maxwell cards.  I recently upgraded from an old GTX570, which ran Starpoint Gemini 2, and Just Cause 2 quite well, Far Cry 3 gave it a hard time.  I haven't looked at any benchmarks, but I suspect the only game in that list that would really make the GTX960 sweat is Far Cry 4 (maybe 3 if you max it out).

Addendum:

X Rebirth has severe performance issues, so there's really no predicting what will run it well.  The situation with that game is unquestionably Egosoft's fault, and you shouldn't hold it against any particular GPU.

Wow, thank you both very much, set and ExpandingMan, for your inputs 😎

@set,

Thanks to list your computer specs. It's good to know that these games play on a 2GB card (currently my i7 mentioned has 'only' 8 gigs, but it has the possibility - and I consider anyway - to upgrade to 16 gigs if necessary).

@ExpandingMan,

thanks very much to elaborate for me, I really appreciate !

I haven't yet taken a look to the exact modell names and specifications of the cards, I only considered the memory which as you tell should not be my primary concern, I think the 4GB card is one of those you mention, but anyway I will follow your advice and read the reviews.

Thanks for the link, it turns out that I have already registered there 1 year ago to enter questions about my dwindling laptop power because of too much gaming 🙂

Do the cards you mention have a PCI Express slot?

Thanks and Greets,

XenonS

 

 

First of all, the amount of memory should most definitely NOT be your primary concern. 

It will be in the near future, when more console conversions will appear.  On the other hand, it all depends on, the resolution  you play your games. I use an older AMD HD 6950 with 2 GB Ram, and I can still play everything (including Elite:Dangerous) in Full HD with a very decent framerate (40FPS upwards I think).  It's a bit trickier if you want to play games in higher resolutions. (But I consider it quite extreme. I recently bought a new Full HD 48" Sony Bravia, and even the rolling demos of X2 and X3 looked fantastic with a little bit of 4x antialising).  

 

 

Do the cards you mention have a PCI Express slot?

The standard now is PCI Express 3.0.  Certainly all of the nVidia 900 and 700 series have it.  I'm about 90% sure that all of PCI-E 1.0, 2.0 and 3.0 are backwards and forward compatible, but I'm pretty sure that 3.0 has been around for a long, long time.  Suffice it to say, unless you have a pretty ancient motherboard, you shouldn't have to worry.  (The last standard was "Advanced Graphics Port" or AGP, for those of us old enough to remember.  PCI Express started mid 2000's maybe?)

 

 

I haven't yet taken a look to the exact modell names and specifications of the cards

Remember, the ultimate guide is always benchmarks.  You don't need to be an expert in the specifications to make a purchase.  Besides, it can be VERY hard to predict what exactly the specifications imply about real-world performance.  You want to look at average FPS in real games like Far Cry, Battlefield, Shadow of Mordor, that sort of thing.  That's the only thing that will really tell you how well a card performs.    

 

 

It will be in the near future, when more console conversions will appear.

I really don't see it happening, and I'm not sure what console ports have to do with it.  Like I pointed out, a few games lately have had eyebrow-raising memory requirements on paper, and yes, the fact that the new generation of consoles is slightly less primitive allows that to happen, but I'm sure nVidia and AMD will continue to equip their chipsets with sensible amounts of memory, even on the reference models, like they have been doing for as long as they've existed.  The amount of RAM on video cards has been rising since the 90's, and in all my years building computers I don't think video memory has ever been a significant bottleneck.  Case in point: there was all sorts of uproar about the fact that the new Maxwell chipsets would only have a 256-bit memory interface, and a significantly worse memory bandwidth than their predecessors.  But, lo and behold, they are still the best cards on the market by just about any real-world metric.  (Granted, you can find a few cases where the R9 290X outperforms the GTX980 due to video memory, but with the exception of texture-fill benchmarks, most things go nVidia's way.)

So, will we need more and more video memory as time goes on?  Of course.  Will there ever be a day when we can say "Oh, that card is crap and that other card is way better solely because it has an extra 2GB of RAM."?  I very much doubt it.

In the end, if you can stretch it for the 970, go with that.  It just so happens to have 4GB of memory, which is the maximum these days for anything which is not comically overpriced.   

 

 

I really don't see it happening, and I'm not sure what console ports have to do with it.

PS4/Xbox one have 4GB unified memory, so for console ports you may need at least a 3GB Graphics card, since most of them are not optimised for PC. (For instance Watch_Dogs demanded 4GB, for higher resolution textures). 

I think the GTX 970 has a memory usage problem (anything over 3.5GB) - be wary!

 

 

PS4/Xbox one have 4GB unified memory, so for console ports you may need at least a 3GB Graphics card, since most of them are not optimised for PC. (For instance Watch_Dogs demanded 4GB, for higher resolution textures). 

That in no way implies that we will have to be any more concerned about video memory as a spec than we have been in the past.  Most newer cards have 4GB, cards with significantly less than 4GB in most cases will lack either the memory bandwidth or processing power to properly utilize it.  The point I'm trying to make is that you don't go shopping for graphics cards by how much memory it has.

I think the GTX 970 has a memory usage problem (anything over 3.5GB) - be wary!

Again, look at benchmarks.  The problem showed up in benchmarks designed specifically to test memory transfer, in practical terms it's pretty much irrelevant.  See  http://www.pcgamer.com/why-nvidias-gtx-970-slows-down-using-more-than-35gb-vram/

 

 

Most newer cards have 4GB, cards with significantly less than 4GB in most cases will lack either the memory bandwidth or processing power to properly utilize it.  The point I'm trying to make is that you don't go shopping for graphics cards by how much memory it has.

Don't get me wrong!! I agree with you. I am just saying that for newer cards, a 4GB memory is worth the additional cost. 

 

 

Again, look at benchmarks.  The problem showed up in benchmarks designed specifically to test memory transfer, in practical terms it's pretty much irrelevan

Also agree with you. If I had to beleive benchmarks I should have bought a new card ages ago!!!