Right, so..
Refreshing a thread all night on Thursday for some GPU drivers has to be a low point in my life.
I think I might have had an issue with the 14.12's, as every time I tried turn Vsync on, games would instantly crash. Not a huge issue as I tend to turn it off at 2160p anyway. I noticed it when Benchmarking Thief, and when I tried VSYNC on in Far Cry 4 and Assassins Creed: Rogue.
So late on Thursday night, I ended up using the media drivers that were leaked and was disappointed with Far Cry 4 results at 4k, as I was getting bad stuttering. I said so here:
http://forums.overclockers.co.uk/showpost.php?p=27799277&postcount=2229
When the 'official' beta driver did eventually come along on Friday, I installed them and it essentially broke my Windows 10 tech preview (10041) to the point that I couldn't fix it, and I'm fairly experienced about getting things back up and running.
At that point I was seriously close to ordering 2x Titan X's for 4k SLI...
Fast foward to the weekend and I did a fresh install of Windows 10 from a USB (previously it had updated from Windows 8.1) and installed the Beta 15.3 drivers. So far so smooth.
Out of curiosity I tried Far Cry 4 last night (when I should have been going to bed) and lo and behold it suddenly worked flawlessly! I even enabled Triple buffered VSYNC without it crashing, and though there is a slight input lag now, the stuttering has gone away completely and I was able to ENJOY THE GAME! (at last).
That was
3860 x 2160 @ 60hz
Ultra settings + MSAA off + No NVIDIA Gameworks features enabled.
V-SYNC on
Triple Buffering on
Also, Battlefield: Hardline performance seems better. Can't say for sure if the drivers did anything or the fresh windows install, but again there isn't any perceptible stuttering on the single player campaign any more, which I had previously noticed on the Prologue mission.
So anyway, these drivers have improved things for me, and I no longer have to consider spending £1700 (!) on Titan X's, when I am pretty sure that
A) AMD's high end option will be a lot more cost effective.
B) Nvidia have already said Pascale will have 10x the performance of Maxwell, and that's due out the end of the year according to their graph.
System spec:
5930 k @ 4375Mhz
16GB DDR4 3000Mhz
AMD 295x2 / 290x reference crossfire
Windows 10 Tech Preview (Version 10041)
Samsung 850 Pro
Panasonic 58AX802b 4k TV