There are a number of graphics cards on the market that are marketed as fanless and use integrated heat sinks to provide passing cooling for the GPU. The issue with these cards is that they are designed for use with 'typical' cases and depend on airflow from active cooling provided by the other fans installed in the case. As our cases tend to be very compact and do not provide any forced airflow, passive cards should not be used as they will likely overheat. If you do want to install a discreet GPU in a passively cooled case, it should be one that has specifically been designed for GPU cooling (such as the DB4), or modified to provide GPU cooling via the case heat sink.