X-bit labs

Intel Celeron D CPU: Budget Processors from Intel Acquire Prescott Core (page 7)

Category: CPU

by Ilya Gavrichenkov

[ 06/25/2004 | 06:15 AM ]

Overclocking

Now let’s see how big the overclocking potential of the new Celeron D processors is. Theoretically, the 90nm Prescott core features greater frequency potential, which makes Celeron D processors better overclockable than the older Celerons. On the other hand, these CPUs are based on Prescott C0 core stepping, which is used only in Pentium 4 processors with 3.4GHz frequency. However, we have already managed to easily overclock these processors up to 3.6GHz with simple air cooling involved. Celeron D generates less heat than Pentium 4 that is why it can turn out even better overclockable than the Pentium 4.

We had two Celeron D processors on Prescott core in our lab with the nominal frequencies of 2.66GHz and 2.8GHz. To study the frequency potential of the new processor family we decided to overclock both of them. However, during our overclocking experiments it turned out that the standard cooler shipped with Celeron D is too weak to ensure sufficient cooling for our testing participants. During work both overclocked Celeron processors got overheated real quick, which resulted in system instability. Therefore, if you are planning to per4form some Celeron D overclocking make sure that you have a good cooler at hand. During our tests we used one of the best air cooling solutions from Zalman – CNPS7000A-Cu.

The second thing worth mentioning is the fact that the maximum frequency these processors managed to reach during our overclocking experiments is highly dependent on the power voltage. In other words, by increasing Vcore above the nominal, which is 1.375V in our case, the stability threshold for the CPU got higher. This Prescott’s behavior is a direct opposite to what Northwood core did, when the overclocking results hardly got any better with the processor Vcore growth. That is why to achieve better results we increased Vcore up to 1.475V for our testing participants. This 7% Vcore growth gives us some hope that the processor resource will not get too much smaller and it will not die earlier than expected. The first one to go through our tests appeared Celeron D 335 processor with 2.8GHz clock frequency. Keeping in mind that the FSB frequency of this CPU is 133MHz, the multiplier should equal 21x. When we overclocked this processor, we managed to increase the FSB frequency to 170MHz without losing any of the system stability.

As a result, the CPU clock frequency grew up by the good 28% above the nominal and reached 3.57GHz. This is actually a pretty predictable outcome proving that the frequency potential of the Prescott C0 core stepping is about 3.6GHz.

The second CPU we overclocked, Celeron D 330, works at the nominal 2.66GHz and features 20x clock frequency multiplier. During overclocking all the conditions were the same as in the previous case, but we turned out to be luckier this time: we managed to increase the FSB frequency from the nominal 133MHz up to 190MHz.

As you see, the frequency of the overclocked Celeron D with the 2.66GHz clock rate grew up to 3.8GHz: the gain made 43%. This way, we can conclude that even among Celeron D Prescott with C0 core stepping there are highly overclockable pieces, which can contribute a lot to the overall system performance. To prove this statement of ours we have also included into the further performance analysis the results for the Celeron D 330 overclocked to 3.8GHz.