Took a chance buying a new, but cosmetically damaged Tesla k20c off of Ebay. Had a small ding on one corner so I got it for pennies on the dollar. Works perfectly! Being a headless GPU compute card, I can change the motherboard bios to TCC (Tesla Compute Cluster) mode letting the hardware run without any overhead from MS Windows. In TCC mode my test renders were 50% faster, so it's worth the trouble to see if your headless GPU can run in TCC mode; Titans can... possibly others as well. Combined with the Quadro k5000 the nVidia drivers go into Maximus mode. Redshift screeeeeams!
Redshift GPU computing on the Reading Nook scene. This used to take hours to render with Mental Ray.
Derek Jenson Blog
My website serves to archive experiments, document projects, share techniques, and motivate further exploration & artistry in 3d space.