Asrock 4CoreDual-Sata2 modS

( This Web page holds a list of pictures and descriptions related to few modifications i made on a 4CoreDual-Sata2 motherboard based on the informations i have found on the Net)
( Questa pagina Web contiene un elenco di immagini e descrizioni relative ad alcune modifiche che ho fatto su di una scheda madre 4CoreDual-Sata2 basandomi sulle informazioni che ho trovato in rete)

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Vagp mod (view 1)

Here you can see a 10K Ohm trimmer as replacement of the same value SMD resistor, labeled on PCB as R2471.
The trimmer, also named Variable Resistor (VR), is placed between
IC LM324 pin 2 and ground.
While rotating the VR cursor, Vagp (from which the North Bridge chipset VIA PT880Ultra takes part of its electrical supply) change as well.
Next to the trimmer you can see a toothpick and the soldering iron bit, that was placed there just to let the observer to have a better idea of the real dimensions of the viewed electrical components.

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Vagp mod (view 2)

4CoreDual-Sata2 BIOS provide "AGP Voltage" option where the user can choose one of these values: Auto, Normal, High.
When set to Normal, Vagp is 1,60V while when High and Auto are set, Vagp is 1,61V; very tiny difference indeed.
Setting the VR at about half of its max resistance, it was easy to raise Vagp till 1,75V.
Related link: 775dual-vsta VDDR mod (by Mallet)

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R2471 resistor

This is the SMD resistor (Surface Mounted Device) that was removed from the motherboard and replaced with the trimmer .
The 01C code that you can read on the resitor, means 100.000 ohm (10Kohm) resistance value; code 01 means 100, while the C letter means a multiplier of 1000 (100*1000 = 100.000)

SMD code link:

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The VIA PT880 Ultra chipset

Here you can see what is covered by the alluminium heatsink placed between the CPU socket and the AGP slot.

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Vagp Mosfet heatsink

The Mosfet placed between the AGP and PCIe slots, provide Vagp voltage and current; an excessive increase of Vagp voltage could lead, with the lack of any heatsink, to heat up the Mosfet till to burn it. The picture show a raw HS solution made of retievals parts.
To join mosfet and alluminium stripe was used an adesive thermal pad taken from the package of an Arctic Cooling Silencer NV5 vga cooler.

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This picture is centered at the SMD resistor with code 1BC (15.000 ohm) written on it; this resistor "drive" one of the LM324 four operational amplificators, from which CPU VTT voltage is derivered; the lower the resistance, the higher VTT voltage.
Easiest way to lower the SMD resistance is to "join" its edges using graphite from a pencil; it's a so called "pencil mod".
Related link: 775dual-vsta VDDR mod (by Mallet)

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VTT control trimmer (view 1)

The "pencil mod" is very easy to do and doesn't require special tools or skills, however it doesn't let to do a "fine tuning" of the resulting resistance and, therefore, you could end with a too much high VTT voltage and a damaged CPU (standard VTT voltage is 1,2V; max 1,55V according to Intel specifications ).
So, i choosed the more difficult but "safer" way of replacing the 15Komh SMD resistor with a variable 10Komh resistor joined to another 5600ohm resistor.

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VTT control trimmer (view 2)

Same mod as seen in the picture above; just another point of view.
One leg of the trimmer is connected to ground; another leg to LM324 pin 9, through the 5600ohm resistor.
Therefore the max resistance is 15,6Kohm, while the min is 5,6Kohm that corresponds to a CPU VTT voltage of 1,48V (note: is better to keep CPU VTT lower than Vcore).
Related links: Understanding GTL Reference Voltage, Adjusting A/GTL+ Levels for Increased FSB Signaling Margins and Overclocking (by freecableguy)

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Vddr mod (first version)

The APW7120 IC (Integrated Circuit) is responsable of providing reference voltage for RAM electrical supply.
Following the instructions provided by Mallet i had connected a variable resistor between the APW7120 FB pin and ground.
The goal is to raise Vddr till 2,1V (starting from default DDRII 1,8V voltage).
Unfortunately the Vddr misure point referred by Mallet is wrong; the right one is located next to VT3 PCB label that you can see in the picture.

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Vddr mod (second version - view 1)

This is a better solution than previous.
Here there are no more wire, the VR is firmly joined to the mother board, the FB to ground route is as short as possible.

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Vddr mod (second version - view 2)

Same mod as seen in the picture above; just another point of view.
4CoreDual-Sata2 BIOS provide "DRAM Voltage" option that can be set to one of these values: Auto, Low, Normal, High. While using DDRII RAM module, Vddr voltage misured at VT3 point, without Mod, was 1,86V when "DRAM Voltage" set to Low; 1,96V when "Auto" and "Normal"; 2,06V when High.
Voltage values misured at the Mosfet leg pointed by Mallet are lower of about 0,15V!; in most case a 2,06V Vddr voltage is enough (for DDRII) so there could be no need of this mod.

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vCore voltage regulator

Here you can see a close view of L6714D IC and the 0hm SMD resistor (just a bridge), at the up-right of IC, that will be replaced by a 47000 ohm VR.

Related link: Volt Mod done right - ASRock 775dual-VSTA / L6714 (by gustep12)

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Trimmer vCore installed

Here you can see the 47Kohm VR soldered on the mother board in place of the SMD bridge; one leg of the trimmer is connected to L6714D pin 32 (OFFSET pin) through the trace that starts from the SMD pad; the other VR leg is connected to ground (you can see the wire that end to the empty capacitor area) through a 22Kohm resistor (you can partially see it from behind the tall capacitor; note the hot glue drop).
With this mod i have easely and precisely raised Vcore of 0,07V.

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Voltage misuration points

VT1 = Vcore; VT2 = VTT (1,2V. misured 1,33V); VT3 = Vddr (1,8V default for DDRII, 2,5V for DDR); VT4 = Vagp (1,6V); VT5 = DDR I/II SDRAM Termination Voltage (~1V)

Questions and comments are welcome.
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Visits since May 23 2008


edited using:
GNU Image Manipulation Program
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