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Leadtek Geforce GT 220 Extreme Overclocking Experiment

Overclocking/Overclocking Tests by massman @ 2009-11-10

We pour some -180°C LN2 over NVIDIA´s 40nm GPU to see how high it will scale. With the help of some voltage modifications we are ready to breach some world records at the low end of the video card scale.

Voltage modifications and memory

Voltage modification

The electrical scheme of this low-profile, low-end graphics card is a pretty straightforward one. There are two voltage regulators: one which takes care of the voltage for the core, the other one taking care of the voltage for the memory. Lucky for us, the used voltage regulators are basic, so there's no extensive VID table or OCP/OVP issues at very low voltages. No, as you will see on the example picture below, the voltage modification for this card is a simple "FB to GND".

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The datasheet of this voltage regulator is attached to the forum thread of this article.

As for the value of the VR's: I've found out that if you are planning to go beyond 1.6V Vgpu, you might prefer to use a 10k ohm resistor as it will be easier to set the voltage to an exact value. However, more than 1.6V Vgpu is in most cases not necessary as you will see.

Voltage read-out

Please, when you alter the voltage of either core or memory, always double-check the voltage you set! It's of utmost importance that you always know what voltage you are running at; not only because of safety precautions, but also for further analysis as the more you know about MHZ per Volt scaling, the better you'll be able to tune your graphics card for optimal performance.

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Memory Specifications

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The graphics card is provided with 1.2ns Hynix DDR3 memory which, although rated at 833MHz, runs stock at 800MHz.

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The memory voltage has an upper safety limitation to 1.975V, so be careful when increasing the memory frequency.

Comment from Massman @ 2009/11/10

John, could you attach both PDF's to this thread? People who are no OCTB-member can't seen the voltmod thread.

Comment from jmke @ 2009/11/10

done

Comment from Massman @ 2009/11/10

Thanks.

I'm actually tempted in buying another GT220 to check for overclockability :-)

Comment from Kougar @ 2009/11/16

Interesting read.

Since the memory chip temperatures are obviously holding the core/shader speeds back, wouldn't it not be very hard to jury-rig an inverted peltier block, hot side on the chips? Wouldn't take very much, adjust the peltier voltage as needed to keep them just above zero centigrade... perhaps with a pot that allowed extra spacing. Or direct heating the other side of the PCB directly underneath the memory solder points, sort of like an inverse waterblock for the memory if it could be insulated from shorting.

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