A7V-133 Voltage Mod

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This is a serious motherboard modification which might damage your motherboard or CPU. Neither the author or Overclockers.com will be held responsible for any damages should you elect to implement what is described herein.

A few weeks ago, I mentioned that I had modded the voltage on my Asus A7V133 motherboard and that the old trick I had used on my A7V (the
one shown on Tom’s Hardware) didn’t work on this new board. I came up with a new trick and told Joe about it. He asked me to write up an article, so here it is.

A quick overview of how this mod works

The resistor runs between the VFB pin, which I believe stands for Voltage Feed Back, and ground. It distorts the signal coming into the VFB pin so that the voltage regulator thinks it’s not putting out enough voltage, and compensates to fix that problem.

The original instructions per Tom’s article had a wire run from one SMD resistor to another SMD resistor. This worked great on my old A7V,
even though one of the solder points that was supposed to have a resistor didn’t. When I upgraded to an A7V133, I quickly tried to do the same thing; I had heard from numerous people that the same mod worked fine. I even told people that it’d work, and had heard back that it did work for them.

Well not for me. I tried redoing it several times, thinking maybe I was getting a bad connection, but it just didn’t want to take – the voltages were unchanged. So I went back to the wiring diagram.

One end is connected directly to ground. OK, no problem, my whole case is a ground, so I ran that directly to the side of my case. The other
end connects on the far end of a 4.12k resistor, which runs back to the VFB pin on the Voltage Regulator IC. So what was essentially happening was that I was running VFB through 28K ohm to ground.

So I grabbed a 28K ohm, 1/4 watt resistor, and attached an ultra thin wire to the ends of it. One went to ground on the side of the case, and the other I connected directly to the VFB pin on the voltage regulator.

Success!

My voltage now goes all the way up to 2.4v, which is how much my green core 750 needs to be stable at 1.1 GHz. Before the mod, the CPU wouldn’t go over 966 stable.

Here are some pictures of what I did:

Here’s where I hooked up the ground end of the mod, side of the case, near the ATX ports.

Here’s an overview of the mod; I wrapped the resistor in shrinkwrap tubing.

Here are two nice close pictures of the connection I made on the voltage
regulator IC. Not as easy as it looks.

After I booted the computer to make sure the mod worked, I added some epoxy

to hold the mod on – not cool to get to a LAN party and find that your voltage mod fell off because of all the shaking on the way there. Nothing like being stuck running at low speeds while your at a LAN party.

Now, keep in mind that doing this will severely increase your CPU’s wattage output.

My CPU at 966/1.9v put out 61 watts of heat. But at 1.1 GHz, 2.4v it puts out 101 watts of heat. I’m watercooling, and even that has a hard time removing that much heat from such a small contact point. Also, running a blue core over 2.1v has resulted in severe damage to several CPU’s from what I’ve heard.

Oh, and the BIOS voltage controls don’t seem to work anymore after
doing this mod – you have to use the voltage jumpers to set your voltage. I’m not sure what causes this; if I had to guess, I’d say that the BIOS comes up, looks at the voltage, panics, and refuses to set the voltage anymore. At least, for voltages below the CPU default; above the CPU default, they seem to work in BIOS. (eg, CPU default = 1.7v, I can do 1.75, aka 2.3v) through 1.85 (aka 2.4v) in the BIOS, while setting the BIOS to 1.4v to try and get a more reasonable 1.95v or so, doesn’t work – the CPU stays up around 2.2v.

Things I’ve noticed with my voltage at 2.4v

The voltage regulators aren’t as accurate anymore. My voltages in MotherBoard Monitor can swing from 2.35v to 2.43v when I’m set for 2.4v. I’d say 90% of the time, it’s at 2.4v, but it does swing a lot. This could also have to do with my power supply; my +12v is at +13v when I’m running the CPU at full tilt (I have a PowerMan 300 watt supply).

Oh, and the Hardware Monitor in BIOS reports the voltages quite a bit lower than MotherBoard Monitor does, but it’s always done that, even before the mod.

Hope this helps; if you kill your board, or your CPU, or both,
I’m sorry – don’t kill the messenger. 🙂

UnaClocker


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