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  How to Volt-mod your GeForce 4 videocard

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All modifications described henceforth will void your warranty and if not done with proper care can result in rendering the product non functional. Neither the author of this article or TechSpot shall be held responsible for any injury incurred or hardware damage when performing these modifications. So proceed at your own risk...

 

Some Background information

Although with significant differences, one could say that GeForce4 Ti4200 cards are based on very similar hardware than most Ti4600 cards (our overclocking target). The first difference you will notice when looking at both cards is that Ti 4200’s are much smaller; being a slower product, most manufacturers save on production costs by reducing the power circuit significantly. This card actually has a power circuit more comparable to that of the GeForce3 than the GeForce4 Ti4600. The memory used is also slower to reduce costs; this is actually what makes the “high-end” cards so expensive since memory accounts for much of their total cost.

Exact specs among Ti4200’s can vary, you will probably find memory in the 3.5-4ns range from most of the Taiwanese manufacturers, and if you paid a little extra for your card perhaps 3,3ns memory. You divide 1000 by the nanosecond rating of your memory, in the case of 4ns memory this is the same as 250 MHz, or, if you prefer, 500 MHz DDR which happens to be the clock speed NVIDIA has officially set for the Ti4200.

Just for your reference the Ti4400 usually uses 3,6ns memory and the Ti4600 2,8ns memory.

If we are to compare the similarities between the cards we can take a look at the GPU, these are just the same on all Ti boards, the only thing that will differ is in the text printed on top of them, but it’s really the same chip. As you might be aware the Ti4200 is clocked at 250 MHz for the core while the Ti4600 is clocked at 300 MHz, as you might guess this leaves quite a lot of headroom for overclocking.

The card I will be using for this modification is Gainward’s GeForce4 Ti 4200 64MB variant (not their “gold model”.) I paid $150 for this card here in Sweden.

 

Overclocking before Volt-modding

Using standard cooling I was able to get this card right out of the box up to a stunning 320mhz for the core and 580mhz for the memory that’s a 28% increase in GPU speed and 16% in memory speed, quite impressive.

In an attempt for achieving a higher speed I swapped the standard cooler for a watercooler generously provided by CPUFX INC. Though, to my disappointment, I was not able to overclock a single MHz more, the reason for that can be seen below.

 

    

As you can see the GPU is not flat and it did not make contact with the cooler, a quick measurement above the GPU showed an egg cooking 80°C temperature! To remedy this I took some 600-grit sandpaper and sanded the core down until I got it flat, the result shown below

 

 

 

After this the core came down to a more humane temperature of 65°C using standard air-cooling when tested at 320mhz just like before I lapped the core. This gave me an 8,5mhz increase in overclocking resulting in 328,5mhz.

Now that the GPU had been pushed to the limit without volt-modding I turned to the memory. My card came with 64mb of 3,6ns EtronTech memory without heatsinks, the maximum speed I managed to get out of them artefact-free was 580mhz, the “Point Sprites” test in 3D Mark 2001 was used to reveal when overclocking was causing visual glitches (see pic below).  

 



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