Antec 430w TruePower: Any way to Vmod this ??

[celemine1Gig]

Hmm, I just did the mod on my Mapower 500W PSU, which does have internal pots, but maxes out at 3,46V with the internal pot for the 3,3V rail.

Now with the mod in place I get 3,49V regardless on how I turn the pot.

HELP, please? I need that PSU tomorrow evening in my system with 3,6-3,7V on the 3,3V rail. So if you can help me, please post here.

Big THX in advance!

Greets

Ingmar

Edit: Problem solved! I just had to turn the Pot indside the PSU to zero and then turn the added pot in the sense line and it worked like a charm. Running 3,65V right now on the 3,3V rail.

[serialkiller]

ok, my truecontrol 550w sucks too much for me so im considering a new psu...
It has come to the point where i cant upgrade my cpu (2500+) to a 3000+ cause then the 12v is too low and my pc shuts itself off...

Which PSU should i buy then, preferably one iwht adjustable pots inside?

[Nebulous]

Originally posted by serialkiller
ok, my truecontrol 550w sucks too much for me so im considering a new psu...
It has come to the point where i cant upgrade my cpu (2500+) to a 3000+ cause then the 12v is too low and my pc shuts itself off...

Which PSU should i buy then, preferably one iwht adjustable pots inside?

There's only 3 that fit that category:

Fortron
Sparkle ( Made by fortron and cheaper )

And the big daddy of them all: PC Power&Cooling.

All 3 have adjustable pots inside to adjust all 3 rails.

Also if you're considering getting rid of that 550w cheap, pm me

[serialkiller]

do you happen to know (europe maybe?) where they sell them for a fairly good price or less?

PS. YGPM

[Nebulous]

Awman, sry. I thought you was in the states. Maybe another member here that's in europe can help you out.

PM replied.

[serialkiller]

anyone has an idea where to find these PSU's? (worldwide or europe)

[crotale]

I thought a strictly electrical explaination to this vmod with some pics could be something.

Without the mod, the PSU just reads the voltage with no (or very little) voltage drop
from the ATX connector, with reference to ground.
One idea was to just add an inline resistor, and change it's value.
Depending on the sensing circuit
in the PSU, this could work, but most devices (for example DMM (Digital Multi Meter))
has very high internal resistance, which means you need a really high resistance.

The other method is to add a small inline resistor and another varaiable resistor to ground.
Like this schematic:



What we basicly do is splitting the voltage between the Rfix and Rvar. The sensing
circuit is "sensing" the voltage over the Rvar. With a high value of Rvar, most of
the voltage will be over it. If we lower it, the voltage will decrease over Rvar and
increase over Rfix. The sensing circuit thinks the rail is too low and increases it.

This picture is general and the most common way to "fool" the sensing circuit.

As for calculating the "new" voltage, here's how to do it...



Where U_sense is the voltage the sensor will read and U_real is the real voltage.
(This is a formula for voltage splitting)
But we want to know what kind of real voltages to expect with diffrent resistances.
Let's play with the forumla.



Here, the U_real is the new voltage, and U_sense is the initial value.

If we use the +3.3V mod for example.
Rfix = 10 ohm
Rvar = 250 ohm (1k VR turned down some)

U_real = ((250 + 10) / 250) * 3.3 = 3.43

If we take the +12V mod:
Rfix = 68 ohm
Rvar = 2500 ohm (10k VR turned down)

U_real = ((2500 + 68) / 2500) * 12 = 12.33V

Remember: ALWAYS measure the VR/Rvar before soldering it into the curcuit.
*looking at dead FX5900*

Just tell me if something is unclear, and needs better explaination!

EDIT - Variable Resistor (Rvar) must measure approximately 15 to 20 times the circuit resistance of the sensor wire (when you cut the wire measure what the resistance to each end of the resulting cut is plus the fixed resistor). - STEvil

EDIT - Thanks for the input STEvil

[serialkiller]

thx a lot for this scheme mate
think this will solve a lot of questions already

[kchip]

Hi

I have an Antec 430 TruePower and found a vmod for it somewhere else. BAsically my voltages fluctuate and I think its hampering my stabilty while OC'd.

Basically I Soldered a 1K vr to the 3.3 and 5 v sense line near the ATX plug. I thought it was pretty straight forward vmod.

I rebooted into Bios , then Hardware monitoring. NP

Tried changing resistance in both circuits but got NO change in voltages in BIOS. 3.3 never budged from 3.26v and 5v never moved from 4.97


What am I missing? Will this vmod not work after all?

[Nebulous]

Originally posted by kchip
Hi

I have an Antec 430 TruePower and found a vmod for it somewhere else. BAsically my voltages fluctuate and I think its hampering my stabilty while OC'd.

Basically I Soldered a 1K vr to the 3.3 and 5 v sense line near the ATX plug. I thought it was pretty straight forward vmod.

I rebooted into Bios , then Hardware monitoring. NP

Tried changing resistance in both circuits but got NO change in voltages in BIOS. 3.3 never budged from 3.26v and 5v never moved from 4.97


What am I missing? Will this vmod not work after all?

A 1K VR? Um... i think you're better off using a 10k VR instead. i have a 10k vr on each of my rails and they work perfectly.

[STEvil]

and a fixed resistor

[Nebulous]

Originally posted by STEvil
and a fixed resistor

No fixed resistors here.

[kchip]

OK ,

What I undeerstand the above diagram and the vmod described here.

What fixed resistor should be used for the 3.3 and which for the 5 ?


thx for the help inadvance

[kchip]

Nevermind...found my answer

[hax0r]

deleted

[cpl1234]

Hi, I'm new to this voltmodding so please be gentle. This is the first voltmod I've done except for the pencil trick on my old NF7.

I just modded 3.3, 5 and 12 rails after reading the whole thread (took me a while...)

Done all the mods and works good.

However, I'm not sure what's the highest voltage I should put on the rails.

I'm currently running 3.4, 5.1 and 12.2 (in a 3dMloop on a multimeter). Would it help to raise the rails anymore? These voltages made the vcore fluctuation better.

Also, on the first page, I read something about lowering the AGP voltage to stop the Gfx card overheating? Can someone explain that to me?

[Minnyboy]

Originally posted by cpl1234
However, I'm not sure what's the highest voltage I should put on the rails.

I'm currently running 3.4, 5.1 and 12.2 (in a 3dMloop on a multimeter). Would it help to raise the rails anymore? These voltages made the vcore fluctuation better.

Also, on the first page, I read something about lowering the AGP voltage to stop the Gfx card overheating? Can someone explain that to me?

I'm running 3.5-3.6v, 5.4, 12.4v with no problems whatsoever...
I honestly don't think that there'd be a need to raise the 5v or 12v any higher unless you're running a lot of hardware that'd use up all your available molex/floppy connectors...

That's just my opinion...There's a few guys/girls here that run way more than that but that's too overboard imo...

As for the Gfx card overheating....If you got a p.o.s hsf on the Gfx then it'll heat up...But I'm running 1.7v through my 9800pro & 9800XT & when I put my fingers on the card, I do not notice any hotter temps...I know my finger isn't the best temp but I've also measure with a temp probe & it don't make a difference...

It's only when you volt mod your card, that'll make a BIG difference in heat output...

Just my 2 cent & more...

Cheers,
Minnyboy

[cpl1234]

Ok, thanks, running @ 3.5, 5.4 and 12.4 now... No significant improvement....

Haven't tried to push the hardware more though... will try when I have time tomorrow.

[Gk22CoE]

is it possible to only mod one rail?

I did the mod for my 3.3v rail and nothing changed... accually .01 more volts but that's all...

[JohnFish]

Just a quick question. I went to the local maplin store to get the resistors for the mod. Although, I could find the normal 18-turn pots so I got 3 "Square 22-Turn Cermet Preset Potentiometers" is there anything wrong with that? thanks in advance

link to the pot i got

[STEvil]

You're good to go, thats what i used.

[Mrki]

Work this vrail MOD with the LC 550Watt or Thermaltake 480Watt?

[Hell-Fire]

Work this vrail MOD with the LC 550Watt or Thermaltake 480Watt?

The sense wire mod should work on any psu that indeed has sense wires.

[e268]

I need higher volts on 3.3 rail to my UTT ram. I f I mod and raise it to 3.6v or 4.0 volts, would it hurt other equipment? What other equipment uses the 3.3 volt rail? Thanks.