SLI Memory and the EPP Program
What is EPP?
Along with the nForce 590 SLI chipset, NVIDIA worked with Corsair to help improve the state of memory overclocking on an industry wide level. Together the two companies developed what they are calling EPP — enhanced performance profiles. These profiles are stored in a similar way to the standard SPD settings that all memory has now, but extends past the JEDEC memory standards to include other information in the SPD such as command rate and other timing values.
These EPP modules have the ability to set more specifically their optimal settings when the motherboard that supports EPP as well is set to Auto. The full data set in the SPD EPP profile can be loaded or just the standard SPD settings will work if the motherboard BIOS is not capable of reading EPP.
This means that even new modules from Corsair and other vendors that have EPP implemented in them will continue to work the same way on non-EPP motherboards. Just today, OCZ announced their support for EPP as well, so this looks like it could take off very quickly in the enthusiast market.
What is even more interesting is that with EPP, you can basically have more than one set of standard memory profiles in the SPD, allowing the user to choose between them. That means that if Corsair has a single module that can run at 800 MHz at a CAS latency of 4 or 667 MHz at a CAS latency of 3, both profiles can be included and when the user selects one it will be automatically integrated into the BIOS.
SLI Memory and Overclocking
The first EPP memory we recieved from Corsair is the CM2X1024-6400C4 modules seen below:
These are able to run at DDR2-800 with timings of 4-4-4-1T; by far the fastest DDR2 we have seen yet at PC Perspective.
In our nForce 590 SLI BIOS that supports EPP memory, it shows up as SLI-Ready Memory, NVIDIA’s proprietary naming scheme for memory that meets their requirements on the EPP standard and overclocking capability.
In the BIOS overclocking settings, there is an option to set the SLI-Ready Memory at an overclock level that the BIOS will handle by itself. These settings here show a percentage of what the user would like the processor to overclock to at most. Then based on that information, the BIOS will clock the memory as fast as it can based on the EPP profiles while still keeping the CPU within the safe limit that the user has selected. For example, setting this at 10% on a 2.8 GHz processor would allow the BIOS to automatically overclock it to 3.08 GHz and move the memory speed up to over 1 GHz with lower timings.
It all works very well, though it can be difficult to grasp all at once. We’ll go over more of this in our BIOS section later.