Dell™ branded memory available in Memory Selector has passed rigorous quality control and testing, is guaranteed to work with your specific Dell system, is fully compatible, and is backed by Dell service. Generic or substandard products from other vendors run the risk of causing downtime, not only costing the business, but putting the entire system at risk.The speed of the memory currently available may differ from the original system memory, but it has been verified to work with the system. When mixed, the memory will operate at the lowest configured speed, or at the highest speed allowed by the system.