AMD Thunderbird/Duron Investigation & Overclocking Discussionby Anand Lal Shimpi on July 12, 2000 7:09 PM EST
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Tom’s latest article indicates how to physically modify the Thunderbird/Duron in order to adjust their clock multiplier and/or core voltage setting using the “Golden Bridges” that are present on the CPUs themselves.
Thunderbird core voltage settings
Using this newly found information we modified our Duron CPU to operate at the maximum allowed core voltage of the current revision of the Duron processor, 1.85v.
The modification was done by using a conductive pen to connect the two points of the “Golden Bridges” present at position L7 on the Duron CPU. Since the tip of our conductive pen was entirely too big to do a precision job, we simply used the tip of a pin to connect the two points on the "Golden Bridges."
We started by first increasing the core voltage to 1.70v, which only required one modification, then later moved up to 1.80v, which required a second modification and finally 1.85v, which forced us to connect all of the “Golden Bridges” present at L7.
In spite of all of this, our Duron 700, running at 1.70v and finally at 1.85v would not overclock past 700MHz. We could easily underclock it to 600 and 650MHz but even running it at 750MHz was out of the question. This anomaly was present even with our 800MHz and 1GHz Thunderbird parts, the 800 wouldn't boot at any clock speeds faster than 800MHz and the 1GHz part that we ran at 105MHz x 10.0 (1050MHz) wouldn't boot at 100MHz x 10.5 (1050MHz).
The only explanation we could come up with for this was that somehow the clock multiplier was being limited by the original clock multiplier of the CPU. For example, the Duron 700's "Golden Bridges" indicated a 7.0x clock multiplier and while it would work with 6.0x and 6.5x multipliers anything higher than 7.0x wouldn't work. The same situation existed with the two Thunderbirds we tested.
Since we have such a small sample size we can't say anything definite about the status of clock multipliers on all CPUs, we purchased a few retail chips and will test those as soon they come in and report on our findings.
While we are aware that manipulating the "Golden Bridges" that correspond to the FID and BFID pins on the CPU we have yet to successfully find a tool that can be used to cut a connected "Golden Bridge." We will continue to experiment with this as well.