Iray render end point

Dave

when I start an iray DAZ studio render my cpu will go to 100% and usually stay there untill the render is finished , however some times like today it will go to 100% and stay like that for a few hours then drop to 20% even though the render is not finished.the render today was for max samples of 25,000 max time of 12 hours quality 100 iray convergence 100% When i left for work about 30 mins after starting the render cpu was at 100% (it is also set to use my nvidia geforce titan graphics card as well)8 hours later when i got back from work progress was at 43% and number of iray itinerations was at 1,974 but the cpu was only at 20%.Any one know why this is happening .pc is core i7 cpu clocked at 4.5Ghz water cooled 32GB RAM and geforce titan with 6GB RAM

Taoz

Dave said:

when I start an iray DAZ studio render my cpu will go to 100% and usually stay there untill the render is finished

Wonder why it goes so high - mine stays between 50 - 80% most of the time, depending on the CPU settings (old Q6600 2.4G Hz quad core CPU). Several hours of rendering when using GPU also sounds like a lot. Sure the GPU is actually enabled? If the scene is too large for the 6 GB VRAM it will shift to CPU rendering and then it easily takes hours with high CPU.  

Dave

Yes GPU definitely enabled and I can hear its fans speed up after a while it only does that when working hard