truly xtreme

[pucky124]

how do u guys know what resistors to solder onto. for the most part i understand all the mods but ive never seen any explanations of what exactly its doing. i know it increases resistance i assume this follows the volts=amps*resistance law but how do u know the amps r staying the same. also can someone explain to me exactly what a mosfet is.

[blinky]

a mosfet turns one voltage into another, i think
like 5v --> 2,9v-3.3v for vdimm or somthing

and what most vmods are doing is tricking the feedback circuitry of voltage regulator chips, into thinking that they are giving out to low volts, and compensating by raising them. when really they are being raised beyond what its supposed to.

most vmods u add resistance, but some u lower, but im not sure whats happening in those

[DriveEuro]

He's not looking for an explanation of what happens. He wants to know how the people figure out what resistors are needed for what mods and what chips are used.

[craig588]

They look up the diagrams of the Vregs and add resistance to the vsense leg. That's how pretty much every vmod is done.

There are some special instances like removing mc64 that I dont understand, the ones were you remove something seems to be getting rid of some sort of faulty circutry that adds some sort of weird problem. (Usually voltage fluxuation)

[pucky124]

ok im starting to get it but how do u isolate which mosfet controls what and which resistors r on that circuit for u to solder onto. i mean i look at a motherboard and see like a million tiny resistors and some caps but cant figure out where there leading to other than thniking that the manufacturer probably put things together (like memory mosfet somewhere near the ram slots).

[craig588]

you change values in the bios and check what changes. You would want to check components around the area that the voltage is related to.

[bh2k]

usually what happens is when they remove resistors and :banana: :banana: :banana: :banana: like that is because there is a vreg chip, but it's too hard to get to or doesn't have the right vsense line. So, when the trace for the leg leaves and comes in to a resistor they can remove it and put their own VR in to adjust the restance from that point and when the trace ends it goes back to the feedback and it thinks it's giving too little voltage and all that crap blinky said.

[Hell-Fire]

On a moajority of vmods you are only "adding" resistance in the form of adding a VR into the circuit loop. You are actually lowering the overall resistance which causes the voltage to increase.

When you add a VR to a Vreg pin, you are effectively adding a resistor in parallel with the already onboard resistance. Anytime you add a resistor in parallel with another one, you lower the overall resistance of the circuit.

Now, on the instances where you are actually increasing the resistance of a VR in order to increase the voltage in the loop, you have basically added a resistance into a circuit where there may not have been any before. This is typical of vmods where a trace has been cut and you are adding a fixed or variable resistor to the trace. You would start the VR at zero resistance and increase the resistance to increase the voltage in that loop.

Lets say that you check the resistance of a pin on a Vreg and you get 400 ohms. If you add a 1K VR to that in order to raise the voltage, the new resistance with the VR set to 1K ohms is now 285.7 ohms from the previous 400 ohms stock resistance. And everytime you turn that VR to lower its resistance you are lowering hte overall resistance even more.