More P5B secrets uncovered

[bachus_anonym]

I think, this is another good way to show what Tony and FCG are talking about... To show that past 400MHz there is a "dip" in performance, I decided to complete few SuperPi 32M runs, a great bench that can uncover fluctuations in bandwidth and latency.

First, I booted at 400MHz and run 32M at three ratios - 533, 667 and 800. Then booted at 402MHz and did the same. At the end, to show that "dip" may be somewhat reversed (up to the point, unfortunately), I booted at 400Mhz and then once in Windows, raised clock to 402Mhz with ClockGen.

Boot @ 400x9        Boot @ 402x9        Boot @ 400 & CLG to 402

DDR2-800  --> 14:10.969  DDR2-804  --> 14:42.922  DDR2-804  --> 14:06.672
DDR2-1000 --> 13:35.765  DDR2-1004 --> 14:07.297  DDR2-1004 --> 13:32.562
DDR2-1200 --> 13:17.109  DDR2-1206 --> 13:51.891  DDR2-1206 --> 13:13.109

Interesting, eh? Unfortunately, raising clock past ~430Mhz using ClockGen, ends with a crash


EDIT: Oh, yeah... BTW, this is what happens when one compares 516x7 and 400x9, with keeping memory speed as close in both cases as possible:

516x7=3611MHz, DDR2-1032 --> 13:55.625   400x9=3600MHz, DDR2-1000 --> 13:35.765