Double check your clock timings against the reference design for your card. Can get the specs from nvidia site and use a free tool like GPU-Z to read your card's profile and realtime clocks. Out of the box, many models have been clocked higher then the reference design and depending on how far the vendor pushed them it can cause some stability issues in different environments.

The ramped up settings may be fine under ideal conditions, but there are a lot of variables in play that aren't likely to match the lab environment they were tested in. Power supply, cooling, driver tweaks...sometimes things need to be notched back a hair to improve stability. This can be done with free tools like MSI Afterburner or nVidia Inspector.