P5B Deluxe 0609 BIOS FIX Memory 4:5 Problem

[bachus_anonym]

OK, so check this out...

I'm on stock heatsink at this moment and my CPU maxes out at 3.60GHz, 32M stable. So, I first run SPi32M @ 400x9=3600MHz, DDR2-1000 (667MHz ratio, 4:5) and got 13:42.797.
Above result is about right, since at 400x9=3600MHz, DDR2-1200 (800Mhz ratio, 2:3) and same conditions I get 13:15.437.

Then I dropped multi to x8 and it appeared to boot at max 440x8. As it was not very stable, I lowered FSB to 432x8=3456MHz, DDR2-1080 (667Mhz ratio, 4:5) and got 14:40.641. Whoa, that's quite drasatic 58s loss! That's at lower CPU clocks, OK, but higher memory frequency (at least, according to CPU-Z). There would be drop, but this is a big one!

Now, this was for a comparison. I upped mulitplier back to x9 and decided to do one more 32M run at the same CPU clocks as above, therefore lower memory clocks. So, I'm at 384x9=3456MHz, DDR2-960 (667MHz ratio, 4:5) and got 14:11.250, wth

So, now the only thing that came to mind was to run 432x8=3456MHz, DDR2-864 (533MHz ratio, 1:1), which got me 15:11.266.

I repeated 432x8 run again and got the same result as the first time... Some more testing must be done, but it appears to me that perhaps past 400MHz and ratio 667Mhz selected from BIOS, performance really goes down the drain Would that be possible that internal chipset latency gets altered at this point, causing such a drop in performance?