I've come to the conclusion after reading that several of tier one sites also have no clue what this setting does. Read the comments on their sites about it. Anandtech, HardOCP, Xbit Labs, Firing Squad and more have no clue what it does. Anandtech even goes as far as saying NVIDIA refuses to provide information about these settings.
1) Firing Squad
It's also worth noting that the latest BIOS from NVIDIA features two obliquely documented settings: P1 and P2. Apparently, they both optimize certain timing settings in the 790i SPP. We found from OCZ, though, that enabling either setting will prevent stable operation at higher memory frequencies. They should thus be left at "Auto" rather than "Enabled."
Poor memory read performance above 475FSB unless you enable "P1" and "P2" which NVIDIA refuses to document operation of or provide information about.
3) HardOCP (Forum Post Between Daniel Dobrowolski of HardOCP and a Forum Member)
As long as I didn't touch the P1 and P2 settings I didn't have any issues with it.
Was this in the review?
It isn't. I actually didn't encounter data corruption at all messing with those two settings. What I did experience was instability and no improvement in overclockability. So I simply turned those off. However reading about those two settings I have learned that messing with them is one way to cause data corruption. I have not verified this myself.
The board is no longer in my posession so I'm not going to be able to verify that those two settings do in fact cause data corruption. So I'm relating something I've read in other forums and on other sites. I've read this several times so there may or may not be something to it.
4) XBit Labs
P1 and P2 parameters maybe set to Auto or Enabled. They appeared only in the latest BIOS version that is why there are no descriptions of these parameters in the paper and electronic mainboard manuals. And Memory Timing Setting parameter opens a separate page with adjustable memory timings.
At the very bottom of this page before the Memory Timing Settings we see the elusive P1 and P2 options. These are the much discussed options that appear to be disabled at 475FSB and beyond resulting in horrible memory bandwidth.
Even EVGA doesn't say what the heck it does... All they say is this...
The more recent BIOS's includes two new options that can boost memory performance. These options control internal timing parameters. These options can give a boost to performance at higher FSB and DDR speeds. A setting of "Auto" gives you the best overclocking possible. A setting of "Enabled" gives you the best performance possible.
Does anyone know exactly what the heck the P1 and P2 BIOS settings do?