Overclocked wattage?

[gone_fishin]

How do you figure your wattage for an overclocked P4. There is the benchtest.com site but it seems to be controversial with the northwood wattage it spits out or is it? There is also the formula many use, watts=(11 + ocmhz/163)*vcore*vcore. Both methods turn up drastically different numbers. Even if you plug in the stepping default figures from Intel data sheets into the benchtest formula you then get a figure inbetween the two. Are any of these methods correct or is there a better formula?

[CSHawkeye81]

i believe the second one if the best way to test it out.

[S_Wilson]

I don't like the formula you listed. The one that I use is:

Pnew=(Vnew/Vold)squared * (Snew/Sold) * Pold

P=power
V=voltage
S=speed

For instance, my SL668 Northwood 1.6A @2400 and 1.675V

Pn=(1.675/1.5)sq * (2400/1800) * 46.8
Pn= (1.12)sq * 1.5 * 46.8
Pn= 1.25 * 1.5 * 46.8
Pn= 87.75 Watts

My SL63X Northwood 1.8A @2400 and 1.7V 49.6W = 84.44W

I believe this formula to be pretty reliable.

[gone_fishin]

Originally posted by S_Wilson
I don't like the formula you listed. The one that I use is:

Pnew=(Vnew/Vold)squared * (Snew/Sold) * Pold

P=power
V=voltage
S=speed

For instance, my SL668 Northwood 1.6A @2400 and 1.675V

Pn=(1.675/1.5)sq * (2400/1800) * 46.8
Pn= (1.12)sq * 1.5 * 46.8
Pn= 1.25 * 1.5 * 46.8
Pn= 87.75 Watts

My SL63X Northwood 1.8A @2400 and 1.7V 49.6W = 84.44W

I believe this formula to be pretty reliable.

Thanks for the reply and the clear example. I ran into a lot of controversy over this subject when trying to get a C/W on a waterblock I made and I never came out with a clear answer( I was pointed to the other two methods above). The AMD guys would try to insist that a 1.6A @ 1.9v doing 2500mhz+ was only in the 80watt range. Then there's the 88% of max wattage that some use and some don't so it is next to impossible to get a handle on comparing heatsink reviews.