Unfortunately, we couldn’t proceed further without adjusting the CPU voltage. The Sempron 3100+ is rated to work at 1.4v, while other processors of the analogous architecture work at 1.5v, so we decided that it would be safe to raise the voltage of our sample to 1.65v.
This Vcore value let us conquer the next frequency peak – 280MHz of the clock generator. The system was actually stable at 281MHz, too, and hang-ups and instability only occurred at 282MHz, but we rolled back to 280MHz for more stability; the effective CPU clock rate was very impressive anyway – 2.52GHz!
So, it is possible to overclock the Sempron 3100+ processor from 1.8GHz to 2.52GHz without special cooling and with a minor voltage increase. The frequency gain is 40%, which is good even compared to legendary processors, “overclocker’s choices” of previous times.
The memory frequency was 229MHz at that (see the table above).
Unfortunately, it is not possible to set a smaller devisor (1:9). In this case, the memory frequency would equal the clock rate as defined by the clock generator, i.e. 280MHz. Only DDR600 SDRAM modules would be capable of working at so high a frequency, and they are not widely available now. However, the system with the overclocked Sempron 3100+ demonstrates good results even in memory subsystem tests.
As for the temperature factor, our Sempron 3100+ remained rather hot at overclocking. We didn’t enable Cool’n’Quiet technology, since this would affect the test results, but you’d better use it if you care about the health of your processor. It works fine with the overclocked Sempron, by the way. When the CPU load is low, the processor’s driver just reduces its multiplier to 5x. So, if the Sempron 3100+ normally drops its frequency to 1GHz, our overclocked sample dropped it to 1.4GHz, which was good, too.
But back to the temperature. The Sempron 3100+ overclocked to 2.52GHz was about 64°C hot when idle, and as high as 79°C hot in test applications (according to the mainboard’s data). We’d like to note that working at its nominal frequency and voltage (1.8GHz and 1.5V) the Sempron 3100+ was 47°C hot in the idle mode and up to 60°C hot under load in our system.