NotAPimecone

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Nov 18, 2006
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EPP = "Enhanced Performance Profile" Some motherboards can read the EPP off of your RAM and automatically set up the optimized settings. I think this is an nVidia chipset thing (nForce 5 and up). Most high performance DDR2 probably has EPP whether your motherboard can use it or not.

My RAM, for example, is spec'ed for 4-4-4-12 at 800MHz with a voltage of 2.1V, and has EPP. However, my motherboard doesn't know about EPP, so it auto-set 5-5-5-18, 800MHz at 1.9V, presumably this is what was on the SPD. I had to set up the proper settings for the RAM manually in the BIOS.

So, basically, if you're in the market for high-performance RAM, you'll probably be getting EPP even if it's just an extra feature your board can't use, but that doesn't matter because you can manually set the same settings as the EPP yourself.
 

Mondoman

Splendid
It's just a fancier version of SPD, that includes some manufacturer-sanctioned overclock settings and can also include voltage (which SPD doesn't). Both your memory AND motherboard need to support EPP in order for it to work.
As mentioned above, it's only really useful if you don't want to/can't set memory settings yourself.