understanding OVP and how to tweak it.

[Hartmut]

Originally Posted by Hellshealer

currently it has 665 ohms

it does vary by about 1-2 ohms every 5 secs or so when i mesure it with my DMM

it was at 680ish

Ok so you have a Resistance between FB and GND of about 335 Ohm? or 645 Ohm?
if 335 Ohm i would use a resistor with about 1k Ohm because you must be at the very end of your 20k VR when its turned to 645 ohm.
Or is your complete resistance 645 Ohm? than you should trimmed your VR at about 12k and this should not be the problem.

Originally Posted by Hellshealer

no im just using the earth for voltage readout and VR ground

ever thougt about Currentlimitation from the Mainboard? I don't know how much your card takes at the moment but maybe the 12V break down -> APW7068 shuts down -> 12V getting back to ther 12V -> APW7068 gets back to live
Just an (possible) Idea from me.

Does the Vcore raise idle->load or fall?
Could you measure resistace from FB to Vcore so we can figure out the original OVP Voltage (maybe it isn't our Problem).
Do you have an aditional APw7068 Coltroller or something else for Memory Voltagge or is Memory also controlled by the same APW7068?

[Hellshealer]

osrry i messed up the reading for the 1st part. currently for 1.45v the resistance between FB and ground is 531 (corrected in last post)

im useing a X58 4way classy atm so if i need more power from the PCI i can plug that in.

for Vcore 1.45 idle is about 1.47-1.48v load so idle is lower than load

FB to Vcore is 667ohms

and finally this is the only APW7068, the memory is on an APW7120 8 pin controller

[Hellshealer]

also i think you may have just answered my question...

V out is where i measure the vcore from correct? so a VR from FB to that raising the resistance will/should move the OVP abit correct?

[Hellshealer]

bed time for me, ill check back in tomorrow before work!

[Hartmut]

Yes but the Effect of increasing the resistance to Vcore should be the same as decreasing resistance to Ground.
Can you measure the Voltage at FB? How I understand how that Controller works, it should be alsways the same as Reference Voltage(0.8V) so when you lower the Resistance from FB to GND the Vcore increases because th Voltage at FB went down.
So when you change Voltage FB should always have 0.8V and OVP wont throttle.

But you can test to increase Resistance FB->Vcore. Don't know how much you know about electronics but you need to build in your VR in series to the other Resistor between FB and Vcore.

[Hellshealer]

could i use the 3rd leg on the original VR to do it or would i need another VR?

[Hartmut]

If you use the 3rd leg your will always change the resistance when changing Resistance to GND. And don't forget to increase the resistance FB->Vcore you need to desolder the resistor which is there now.
I would first check if our Problem is really the FB Pin. can you measure the Voltage you have at that pin? if it's around 1,05-1,10V we must try to lower it.

[Hellshealer]

dont have to worry about it now....... i blew it up.........

i went to mesure the volts on FB and i must have slipped and now i get no voltage anywhere, no memory gpu nothing........

time to put mah zombie on it when i finish it