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The first K7 Athlon design uses a Slot A motherboard interface that resembles Intel's Slot 1 standard. Slot A Athlons feature a custom casing. This must be removed before installing aftermarket cooling solutions or overclocking boards. Front-side and voltage adjustments are possible from the motherboard, but AMD did implement a physically locked multiplier determined by the configuration of certain resistors found on the backside of the processor circuit board. These resistors can by modified to set multiplier values, but overclockers needed a better way to manipulate the multiplier given the amount of experimentation required to realize overclocking potential.
Enthusiasts soon realized that the electrical connector found along the topside of the processor board was actually connected to the same circuitry as the backside resistor array. A specialized circuit board can be connected to the electrical interface and used to manipulate the multiplier value. These aftermarket boards are commonly called Gold Finger Devices (or GFDs). Several manufacturers have produced GFD designs using dials, switches, and jumpers. Regardless of their configuration, all GFD products operate by the same practical method. Some GFDs even include support for processor voltage manipulation, for those possessing the soldering skills needed to install this extra option.
Some overclocking-friendly Slot A motherboards allow configuration of the cache divider from the BIOS Setup interface, but this is not the norm for consumer-grade models. Many GFDs also include the capability to alter the Level 2 cache divider rate. The Athlon derives its L2 cache operational frequency through a fractional process, as the comparatively slow cache memory is mounted on the processor's printed circuit board. The cache memory is incapable of sustaining operation at the processor's core rate, thus AMD was forced into a frequency-scaling paradigm for the Slot A Athlon K7.
Cache rates can be defined at several intervals from 1/4 to 1/2 the processor's core rate. Decreasing the fractional rate often allows for greater processor overclocking, though the performance impact could actually be negative. The bandwidth-hungry Athlon core requires a consistent supply of information from the L2 cache to sustain optimal operation. Any decrease in the cache rate lowers bandwidth and increases latency, stalling the processor at higher operating speeds. The only way to measure performance impact is through benchmark testing.
Processor-to-chipset bus overclocking of the Athlon K7 is only minimally effective. Most Slot A motherboards contain early revision chipsets, which commonly fail at operation rates beyond 112 MHz (224 DDR). Increasing the motherboard's input/output voltage from 3.3 to 3.5 volts may offer additional returns, but increased cooling of the Northbridge chipset will likely be required. The addition of a 50 to 60 millimeter fan often works well, as many motherboards already have a heatsink cooler. Some Slot A boards reach speeds above 124 MHz when properly cooled.
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