For those who may be new to Gpugrid may wish to read the following document.

http://cs.stanford.edu/people/ihaque/papers/gpuser.pdf

Hence the recomendation to run a tool MemtestG80 for at least 12hrs (ideally 24) for any particular clock to verify your hardwares stability.
Common knowledge overclocking will increase the probability of soft errors which may not be picked up by the system resulting in the successfull completion of a task but returning an erronous result which may affect the overall outcome of an experiment and hence the science.

Download:
http://folding.stanford.edu/English/DownloadUtils