One of the reasons on buying an Athlon 64 FX is its clock multiplier feature, which enables you to configure it as if it were a faster CPU. In our case we increased the clock multiplier of our Athlon 64 FX-62 from 14x to 15x, making it run internally at 3 GHz, a 7.14% increase in the CPU internal clock. At this configuration, the performance measured by PCMark05 increased only 3.37%.
We put the CPU clock multiplier configuration back to 14x and tried to increase its 200 MHz base clock. We could only go up to 218 MHz, a 9% increase, the same result we achieved with Athlon 64 FX-60 and a little bit less than what we achieved with Athlon 64 X2 5000+ (211 MHz). To achieve this result we have to increase the CPU voltage to 1.425 V.
We tried to increase the CPU base clock when it was configured at 15x, however we couldn’t go over 204 MHz with stability. This shows us that Athlon 64 FX-62 is working on the edge, with very little room for overclocking it.