As the GTX 970 has only 3.5 GB of "fast" memory and another 0.5 GB of "slow" memory (due to low Bus speed) you will actually hit the wall at 3.5 GB VRAM usage. 980 Ti is a different card than Titan, performs about the same but with very different memory size and price point.

 

If you're not in a hurry it might be worth to wait for the next Gen NVIDIA cards that will have a new kind of memory (HBM 2) -  much faster and substantially larger with less power needed. Will arrive in Q2 or Q3 2016. Not that long away.

Both, the 980 Ti and the Titan are very expensive for what they offer.

 

Flo

Well, I *thought* that last 0.5GB was a lot faster than it apparently is.  For me, I'll wait for the next nVidia card.  I've had this one a full year and surprisingly the price hasn't dropped much at all.  I think what you wrote is all good advice.  Haven't seen anything in the news regarding next gen products...will search that up.  Thx.

Ouch...Q2 or Q3 2016 for the next gen card is quite a wait. I'll see what the extra RAM does for me, if I still see a performance issue and my VRAM looking stressed in less dense areas, I'll definitely move to the 980 TI to get more headroom.

 

I'll just have to upgrade again once the new cards are released and after a 3 month hold off period to deal with the bugs and issues that usually come with new hardware. 

And as I'm sitting here working on scenery I notice that this time starting XP I'm using beyond 3.9GB (1GB in use with XP closed...photoshop, chrome, firefox w/google maps, WED) but suddenly getting awesome FPS.  Now, I suppose it could be argued that XP somehow got the fast memory below the 3.5GB mark.  Or is it that it's overcast this time?  Would be nice to have some consistency.  Weird.

 

Here's a cropped screenshot.  Not sure why it won't show directly.

 

Screenshot.

 

Ben S. commented a few weeks back on his blog that what you see in those tools is the memory the GPU driver reserves and that this not_necessarily equals what the apps actually needs. There is a lot of variables to take into account here.

 

As the bus interface load is zero in your shot this_might be a case where your card still has some headroom even if the driver already asks for 4GB.

 

But, honestly, this is mostly terra incognita for me.

 

Flo