Strange voltage problem on p5n-e sli

hi all,

i think some of you know me. I am an experienced overclocker but i have this wierd problem.

my rig:
p5n-e sli with 650i chipset with fan added to the heatsink
e4400 (2ghz @ 3ghz) cooled with a zalman 9500
kingston 2gb 667mhz (not overclocked)
6600gt pci-e
200gb sata
80gb sata
antec 450w psu
lg dvd burner
antec nine hundred case

now the issue is difficult to understand and to explain, i will do my best to explain it. my e4400 is overclocked to 3ghz with 1.392vcore and the chipset at 1.5v. now the chipset has those 5 voltage options; auto, 1.2v, 1.3, 1.5v and 1.7v. if for example i leave the cpu to 3ghz and i up the chipset voltage to 1.7v the pc wont boot. infact at 1.7v it will never boot no matter wat fsb it is set at over 1200mhz fsb (300mhz). If i downclock the cpu to example 2.5ghz all the voltage options works and dont prevent the pc to boot. but over 300mhz the only voltage setting working is the 1.2v. the auto, 1.3v, 1.5v, 1.7v wont work and my pc wont boot. now for sure at 1.2v it boots but it wont go pass the bios screen as its not stable enough with 1.2v. over 300mhz or about the pc will boot at 1.2v chipset but it will not pass bios screen even if i MAX the vcore to 1.6v. I know this cpu is capable of more then that.

So i decided to do a test. i used my gf's cpu wich is also a e4400 that was overclocked at 3.5ghz on a cheaper p5ld2 mobo. well when i put it in my pc it does exactly the same thing, same problem. doesnt go over 3ghz (300mhz). It is quite normal that those 2 cpu's wont go over 3ghz because the voltage in the bios seems to be messed up! then if im correct the Asus p5n-e sli supports up to 1333fsb, why do i need to add voltage at 1200fsb for it to work?? even if i try at 1250fsb it wont boot at any voltage i set it at other then 1.2v!

Now dont say it is because my memory. my memory is not linked so it stays at its default speed no matter wat speed my cpu is at. also at 3ghz, 1.393vcore, my cpu is 100% stable tested over night with Cpu Stress MT. the bios is updated to the lastest. It is impossible that my cpu is maxed out.

So why those chipset voltage are messed up and sometimes work or not work depending the fsb it is set at (no logic there)? Why if this mobo support up to 1333fsb do i need to add voltage to the chipset for it to work at 1200fsb?

thx for the reply in advance, and sorry for the messed up explainations.

finch

up

anyone?

I have the same mobo, i was able to get to 1600 FSB easy. Try bumping hte voltage down to 1.4 on the chipset. Even though you have a fan how hot is it getting?

YaY! a reply lol. since then i exchanged the mobo for a identical one and it seems to be less picky. But i still have trouble ocing. I installed a watercooling on my cpu. my idle temp is 23c-33c core temp depending how cold it is outside because my rad is in the window. the chipset is realy not hot i can touch the heatsink with my fingers and i sense no heat and that at 1.7v. before i have put my watercooling i was able to reach 3.5ghz. now im not able anymore. and thats wat i dont like about this mobo it acts picky. for example at 1250fsb, 1.376vcore wich is the auto in the bios, and 1.5v chipset it is 100% stable. at 1280fsb it needs 1.7v chipset and the vcore still at auto it is 100% stable. if i go any higher then 1280fsb like 1290fsb it is realy not stable and sometimes doesnt even boot up, even if i put 1.6vcore. So im wondering if i need more then 1.7v for the chipset to be able to go any higher or it is the the motherboard is picky for certain fsb? anyways it is hard for anyone to answer that question. so wat i am doing right now is overclocking little by little and im building up a chart where i write everything so i can compare at every settings. that way it is easier to understand wat i have to do on the next move and also easier to see where the problem is exactly. if by my own i am still not able to fix it i will post that chart for you all to see and guide me through this.

one little question. do you know if there is any vdrop mod on this motherboard because the voltage drops alot under full load. when in the bios it is set to vcore (auto) i get 1.424vcore on idle and 1.376vcore under full load. and also will it be wise to do a chipset vmod so it can go higher then 1280fsb or is the problem somewhere else?

thx