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Thread: Asrock 525 Power consumption "fix"




  1. #1
    Join Date
    Jul 2011
    Location
    Berlin
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    Default Asrock 525 Power consumption "fix"

    Hello, this is my first thread here.
    I bought a 525 Board and was not really satisfied with the overall power consumption:
    I got 2x1GB RAM, and one Western Digital Eco HDD and one PCI Soundcard (RME DIGI 96). The Mainboard is powered by a pico PSU, which transforms 12V to 3,3 and 5V. The whole system needed 32-36W out of the plug.
    Thats only 10W less what my old P III do consume, and 10W less than a Core 2 Duo in an Dell Optiplex 745.
    The Problem is, that the MB gives several overclocking and overvolting features but no undervolting ability!
    So i searched for the voltage Regulator Manual in the WWW

    The Power Regulation of the 525:

    There are two APW 7120 onboard. One is for the CPU 1,1V Voltage, the other is for the 1,8V DDR Voltage.
    The 1,5V and 1,05V is made with a linear regulator made of a quad opamp and a couple of fets. Those linear regulators are fed from the DDR Voltage as i think.
    Lowering the DDR voltage will also lower the power destroyed in those regulators.
    The Datasheet of the APW 7120 is aviable here:
    APW7120 datasheet pdf datenblatt - Anpec Electronics Coropration - 5V to 12V Supply Voltage, 8-PIN, Synchronous Buck PWM Controller ::: ALLDATASHEET :::

    Modifications:

    As you can see in the Datashet, the voltage is defined by a resistor feetback network. I did not manage to understand the whole schematics on the MB, but i noticed that it's really easy to modify the feedback.
    If you increase the feedback with a smaller resistor R1 (see schematics pdf) you get a lower voltage.
    So i soldered a Poti from the VT1 Pin to Pin 6 of the AWP 7120.Adjusting it to around 50 Ohm yields a V-core of 0,85V-0,87V. And the CPU runs stable at 1,8GHZ! So i changed the pot to a 57Ohm Resistor.
    The Bad thing is, that the overvolting function is less intense.
    The second thing is, that i did some modifications of the DDR voltage. I use my old overclocking RAM (ADATA Extreme Edition), which is able to run at 1GHZ. Here I did the same thing than to the cpu voltage: put a pot between VT2 and Pin 6. This time a resistance around 1,5k gives 1,5V DDR Voltage. I did not have a 2K Resistor here, so i let the RAM run at 600Mhz and it's rock stable.

    Ok, is it worth using the soldier gun? Yes it is!
    The whole PC needs 22W !
    As you can read in the Atom Datasheet, the VID goes from 0,8V to 1,2V. I think Asrock did not use the VID and let every CPU run at 1,1V. So there is a good chance to get a fine undervolting result.

    I don't whant to write a "exact" diy manual, because i don't whant to risk that someone who is not familiar with hardware modding tries this.

    Last edited by Revox; 07-26-2011 at 02:36 AM.

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