hmm dont know if I did something completely wrong here or if I used some weird setting in Agisoft..but the GTX 980 was actually slower at least when looking at the Show info for my chunk.
Pic 1 is on my machine GTX 670, 24gb ram and a xeon 3,47Ghz
Pic2 is the machine with the GTX 980, 24gb ram and a xeon 2.6 Ghz (cant remember exactly) In the open cl settings I had 2 cpu cores deactivated
Pic3 is the machine with the GTX 980, 24gb ram and a xeon 2.6 Ghz (cant remember exactly) In the open cl settings I had all except one cpu cores deactivated
This is just a scan with 18 pictures, maybe it will be much different on a larger scan.