I'm at work right now so I can't check the exact settings, but in Options there is a check box to "Render as separate processes" or something similar.  Also a slider for threads if I remember right.  Try changing these, restart Poser and try rendering again.

Sorry I can't be more detailed - been a while since I had to change these.  If I get home before you check back here then I'll post some more detailed instructions.

i7 5960X, 32GB RAM, GTX 1080Ti, GTX 980 Ti, Windows 10 Professional.  Running Daz Studio 4.11, Poser 11, Vue Inf 7, Photoshop CS4