I was reading about a pencil vdroop mod for another asus mobo (P5WD2 Premium) using the ADP 3181 chip. The P4P800E-Dlx uses a different chip, ADP 3180. However, both chips use pins 17 & 18 to regulate the output vcore voltage droop.
Looking at the spec sheet for ADP 3180 (cartmanea from this site gave me the idea), they give 3 possible configurations - for the greatest output voltage stability they recommend to put a 20k-ohm resistor in parralel with the 100nf capacitor ! This is exactly what the vdroop mod achieves - by putting a 28k-ohm resistor in parallel to the cap we bring the total resistance down from ~78k-ohms to ~20k-ohms.
It gets better - as the resistance needed to be added is very low, graphite can be substituted in place of a variable or fixed resistor(s).
Simply use a pacer (mechanical pencil with a thin tip) and 2H - 2B graphite, and lightly shade between legs 17 and 18 of the ADP 3180 chip. Check vdroop, add more graphite if droop still unsatisfactory, or if vcore rises under load, remove some graphite with a paintbrush or cotton tip.
I did this on my P4P800E-Dlx last night with perfect success.
Before mod: idle = 1.66v, load = 1.54v (1.52v sometimes)
After mod: idle = 1.66v, load = 1.62/63v
UPDATE - after applying more graphite IDLE = 1.66v, LOAD = 1.65v
Results after mod @ 1.66v: *100% 2 x Prime 95 stable @ 3.53 GHz
(before mod was only prime stable at 3.5GHz)
*Benchable at 3.65 GHz
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