really low 3.3V rail

necromanx13x · Mar 20, 2004

really low 3.3V rail / I think I fried my mobo

I just measured my 3.3V rail on my mobo and I was very suprised to find that it was only at 3.2V!! Maybe this is why Ive been having so many damn problems when I push my Vdimm high... So, how the hell do I raise my 3.3V rail? When I measure directly from the aux connector on the psu I get 3.32V so its something with my mobo. I measured the 3.3V rail as shown below.

lemak · Mar 21, 2004

i used

- 100 Ohm fixed resistor
- 5k potentiometer(variable resistor)

lemak · Mar 21, 2004

here my rail voltage screen shot

i/o volt @ 3.6V

vdimm : 3.3V

anyway fsb still stuck @ 242MHz 2-2-2-11 timing

need some vbt mod to rocket up those fsb with this thight timing

vbt stuck @ 1.54V even with vdimm mod... while it should give 1/2 vdimm voltage ... 154V vbtt really holding my fsb back :beer:

necromanx13x · Mar 21, 2004

Oh cool thanks a lot dude but where exactly do I solder the two ends? The 3.3V Vsense to mobo molex and the 3.3V vsense to psu?

lemak · Mar 21, 2004

necromanx13x said:
Oh cool thanks a lot dude but where exactly do I solder the two ends? The 3.3V Vsense to mobo molex and the 3.3V vsense to psu?

look at all those wires at the atx connector...

try searching for 3.3V rail wires (Color = orange)

if u can find there is 2 wire in 1 same pin..... 1 of the 2 should be smaller than the others

that is Vsense for 3.3V rail

Cut the wires and put Fixed resistor between them.... and another 5K Pot to the fixed resistor just like i show above....

ground the wires for the pot... if didnt ground it ur 3.3V rail will be back to normal again

start with 5K resistance... if not enough reduce the resistance on the pot...

GL

necromanx13x · Mar 21, 2004

ahhh alright thanks so much dude, Ill definitely try it out when I get the chance in about 2 weeks when I have a school vacation. What exactly is Vsense though? Also, why exactly does my 3.3V measure so much lower on my mobo then what my psu is actually putting out?

lemak · Mar 22, 2004

man... hope u didnt mod it with 100K fix resistor on that Vsense

that is just to high... sorry i give u wrong link

it should be 100 Ohm ....

if u didnt like this method here another and simple 1...

the idea is to trick psu v sense .... that 3.3V rail is lower than it should.. than this will trigger up ur i/o volt

On mobo I/O V is lower than PSU reading coz many reason... system underload and mosfet efficiency is not 100%...

necromanx13x · Mar 22, 2004

Nope I didnt do it yet, haha. Does that second method work just as well because it seems like it would be a whole lot easier. For that mod can I use any potentiometer above 10k?

Suma · Mar 22, 2004

Btw, I've checked my mobo and it reads 2 different 3.3v rails.
One as described in this picture:

That one reads: 3.44v

And the other one from this pic:

reads 3.31v

Sisoftsandra reads: 3.6v
Which one is the correct one?

Suma.

necromanx13x · Mar 22, 2004

Well, i think i just fried either my mobo or my psu while trying to check the 12V rail from my mobo using the spot on tictacs picture... Please god let it be my power supply. When I checked it my computer instantly turned off and when I try to turn it back on, my computer goes on for a second and then turns off.

Edit: Yeah im pretty sure its my freakin mobo. I tried using a different psu and the same thing still happens. AHHHH GOD DAMNIT. Now I need a new freakin mobo, either another nf7-s or a DFI ultra infinity...

necromanx13x · Mar 22, 2004

Well, it looks like im gonna be ordering a new NF7-S later tonight...

lemak · Mar 22, 2004

necromanx13x said:
Well, it looks like im gonna be ordering a new NF7-S later tonight...

it should be ur processor coz those 12v reading points is so near to Vcore reading points

so while trying take those 12v reading u might shot it with vcore reading.... than 12v will overide vcore on that mosfet n ...... Can u imagine 12V on Vcore.....

sorry to hear that

necromanx13x · Mar 22, 2004

Wait, so you think I may have fried my cpu and not my mobo? That would be awesome!! Is there anyway to tell for sure besides switching in another cpu? What about the fact that when I turn my psu on my mobo light goes on and it starts up for a fraction of a second before turning off. Could it really be that I fried my cpu and not my mobo?

lemak · Mar 22, 2004

Suma said:
Btw, I've checked my mobo and it reads 2 different 3.3v rails.
One as described in this picture:

That one reads: 3.44v

And the other one from this pic:

reads 3.31v

Sisoftsandra reads: 3.6v
Which one is the correct one?

Suma.

the I/O votage should be on the midle leg of vdimm mosfet

dont use that picture.... that reading taken just to make sure where is Vbt voltage reading point.... if u short those middle leg with upper leg of vdimm mosfet...... 3.3V(I/0V) will be running on ur Vdimm... so becareful.....

hope u didnt kill anything while taking those voltage reading

enduracell just killed his mosfet when he shot pin 3 n 4 while trying to measure Vbt reading from Winbond IC ....

lemak · Mar 22, 2004

necromanx13x said:
Wait, so you think I may have fried my cpu and not my mobo? That would be awesome!! Is there anyway to tell for sure besides switching in another cpu? What about the fact that when I turn my psu on my mobo light goes on and it starts up for a fraction of a second before turning off. Could it really be that I fried my cpu and not my mobo?

that is symptom of ur processor might be kill

My frens pc have same issue... we switch on systems running n fan spinning for 3 sec... then auto shutdown....

u should try with other proc 1st see if it really ur proc...

i'm sure it ur processor unless u short it other way round... 12v to 3.3v dual voltage.. that will be diff story then...

necromanx13x · Mar 22, 2004

if it was the other way around 12V to 3.3V what would happen?

lemak · Mar 22, 2004

necromanx13x said:
if it was the other way around 12V to 3.3V what would happen?

Ur processor is alive....

but the other one dead...

necromanx13x · Mar 22, 2004

Aha well hopefully my cpu is dead. Then I could get a mobile 2500+ and that would be pretty sweet and I would actually be happy. I took my cpu out and it doesnt look fried though... Ill have to test it out tomorrow.

lemak · Mar 22, 2004

Athlon Mobile :beer:

might see 2.5-2.6GHz out of it

GL :beer:

ogboot · Mar 23, 2004

this may be an abit issue, my KV7 also shows 3.22 on the 3.3 rail

really low 3.3V rail

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