45nm chips and FSB OCing are doing my head in

[dinos22]

hey fellas

i always approach overclocking through trial and error and most of the bench sessions i spend messing for hours on end testing small bios changes for specific component OCing...like RAM frequency/latency/MHz, motherboard max FSB, mobo most efficient FSB (tight MCH Performance Level) etc etc

well tonight was one of those let's see what FSB i can boot from bios kind of night lol

what's doing my head in is as of late i've had a fair few motherboards that can hit high FSB but for stable FSB i have to drop MHz by a coutry mile

from tonight
Max stable 3D/2D 550MHz FSB
Max 1M SuperPi ~ 575MHz FSB
Max boot FSB ~ 630MHz FSB

this CPU usually gives me 520MHz stable FSB on X38/X48 boards and 530-535MHz 1M SuperPi sort of FSB

on P5B DLX C2 revision i could hit 628MHz FSB screen and 620MHz 1M SuperPi stable

what's going on with 45nm chips and FSB OCing......what am i missing here....
it seems i'm not alone as others are struggling to do some decent FSB OCing (600+ on air and it's clearly possible considering what we've seen on 965 C2 chipset)

Test Setup

• GIGABYTE EP35-DS3P PCB REV 2.1 (BIOS F2)
• E8500
• TTBigTyphoon Air Cooler
• 1GB stick of Corsair PC8500 DDR2 RAM (Micron IC)
• Gigabyte 9800GX2 (i am using it on purpose to see where i could get 3D with this card)
• Seasonic X900 PSU
• SATA HDD

572MHz FSB bios boot
http://valid.x86-secret.com/show_oc.php?id=362739






i'll stick it under single stage when i get a chance to see what cold does........
i've noticed thought that cold didn't help with FSB much as it used to in 65nm chips....

i've noticed some weird behaviour with FSB OCing and volt changes with vFSB, vPCIe, vMCH

i found that for 625MHz FSB post i could use vFSB=+0.25, vPCIe=+0.05, vMCH=+0.225

raising MCH or vFSB or vPCIe would reduce FSB OC

i'll also try different tREF values as i did have some luck in the past with X38 boards

any suggestions or dicsussion on this 45nm FSB OCing topic welcome....i'd like to hear other ppls opinions