1. Modding and overclocking, pt.1
Since recapping didn't help increase/stabilize the voltage going into the CPU, and I need more voltage to overclock, something needed to be done.
The first attempt was naive: Willamettes have 5 pins to set voltage, and grounding all of them sets the voltage to 1.85 V. The 1.6 GHz model, and I think every 423 CPU, uses 1.75 V as a default, which means all but one of the pins are grounded.
20171022_1-vidBridge.jpg
To start I bridged that pin to another one (top right corner), effectively grounding it, hoping the motherboard would enable higher voltage options if the CPU asks for 1.85 V. No dice: max voltage setting is 1.85V, and the max I am getting is still around 1.77 V. Time to read.
The voltage regulator feeding the CPU is the HIP6301, along with companion ICs HIP6601. Looking at the datasheet of the first one, I came upon something interesting: the regulator features adjustable Voltage Droop, set by using a single resistor.
20171022_2-controller.jpg
You can see the controller in this picture, set up vertically under the 4pin connector. The 7th pin on the right side, from the bottom up, is the feedback (FB) pin, basically reads off the voltage/current going into the CPU and adjusts accordingly. If you follow the trace coming out of that pin you come upon a a 2000 Ohm resistor (marked "202"), this is the resistor used for VDroop: it basically reduces the voltage going into the FB pin, and that voltage drop is substracted from the output that feeds the CPU. The datasheet says we can calculate the voltage drop with Ohm's law, assuming a 50uA load current;
VDroop = 50/1000000 * 2000 = 0.1 V, i.e., the reason I can only get 1.77 V when I ask the motherboard to give me 1.85 V. What I did was simply remove the resistor and bridge the contacts,
20171022_3-vDroopBridge.jpg
20171022_4-voltage.jpg
It works! Feeding 1.825 V to the CPU allows it to POST at 2133 MHz. Unfortunately it will not boot Windows, nor will 2080 MHz, even with 1.85 V. The fastest frequency that allowed Windows to boot was 2000 MHz, which I already had before. I want to push for more because 2000 MHz overclocks the PCI bus, which the SATA card does not like at all (I have already ran into problems because of it!)
I'll see if I can come up with something else.
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