Yes I do have the latest driver which could be the issue but the earlier ones won't work with Octane 4 and the latest DAZ studio beta so I am really screwed if that's the reason.
I cannot use Octane at all on my other computer but I can use iClone just a bit limited in scene size, well considerably limited but it works.
So for now at least it might have to be limited to direct X9 and do my character creation on my other PC and my Speedtrees.
I may try the older rougher ones I own from iC5.
980ti has no studio driver.

The most recent known working driver (I am using it) is the "Studio Driver 431.86" from Sept. 4th. If that is not an option for your card, then the 431.xx game driver is what you will need.

Do Octane and Daz actually need 436.xx?

For the trees, try deleting your temp file before you next start iClone 6.5. Also make sure you have updated to the latest iClone 6 version. Download from your account, or update with the Hub.

Yes Octane 4 stopped working with the 30+ drivers until the last two
Was a fuss similar to this here about the latest ones on the Otoy forum
DAZ studio needs the later ones for Strand Hair AFAIK too but unsure know they stressed updating
I may try and see but if Octane fails to see the driver as happened before will need to go back.

yes that older driver fixed it and Octane 4 seems OK with it
I might run into issues with the DAZ studio beta though, not tested yet
Character Creator too now opens