The Radeon HD 4870 is the first retail graphics card to use GDDR5 memory and the 512MB of memory uses Qimonda branded ICs. GDDR5 introduces features and functions that go beyond previous GDDR standards and enables GDDR5 to operate at data rates up to 6 Gbps, three times the performance of todays high speed GDDR3. The memory ICs feature adaptive power management, error compensation, adaptive interface timings and date eye optimization. The ICs being used are part number IDGV1G-05A1F1C-40X, which are entry level GDDR5 chips and are rated for just 4 Gbps. ATI has them clocked at just 3.6 Gbps, so these should have some overclocking head room left in them...