The SPD is a small EEPROM that normally stores basic information about memory, such as its latency settings, manufacturer, and serial number. EEPs add parameters to unused areas of the SPD chip in the form of either two "Full" profiles or four "Abbreviated" profiles. According to NVIDIA slides snapped by Legit Reviews, abbreviated profiles specify voltage, command rate, CAS, tRCD, tRP, and tRAS latencies, while full profiles add signal drive strength settings, write recovery and active refresh settings, and delay and setup times. NVIDIA says these settings will simplify overclocking on "properly-designed BIOSes," namely those for nForce 590 SLI platforms, without breaking compatibility with unsupported systems.
To complement NVIDIA's chipset support announcement, Corsair is announcing the adoption (PDF) of EPPs in SLI-ready TWIN2X2048-6400C4 and TWIN2X2048-8500C5 matched memory pairs, which are scheduled to hit shelves "later this month." The 2 GB kits run at effective clock speeds of 800 MHz and 1066 MHz, respectively, with 4-4-4-12-2T and 5-5-5-15-2T timings. In addition, Corsair says all upcoming XMS-series DDR2 memory modules will feature EPPs, and NVIDIA claims other memory manufacturers are expected to follow suit.