X-bit labs

Intel Pentium D 920 and Pentium D 930 Processors (page 4)

Category: CPU

by Ilya Gavrichenkov

[ 03/21/2006 | 08:24 AM ]

Overclocking

Low price is not the only attraction of the youngest CPU models. These solutions are usually very popular among overclockers, because they boast the highest frequency gain that can be obtained during overclocking. So, we couldn’t disregard this important matter and paid due attention to overclocking experiments with these CPUs.

The test platform we assembled for our overclocking session was built around ASUS P5WD2-E Premium mainboard. The memory subsystem consisted of two Corsair CM2X1024-6400PRO memory modules. Besides that the platform features NVIDIA GeForce 7800 GTX 512MB graphics card and Western Digital WD740GD HDD. We decided to replace the boxed cooler with the more efficient Zalman CNPS9500 LED.

First of all I would like to make a few general comments about the overclocking of any Pentium D processors on Presler core. Just like their predecessors on the 90nm core, the new Pentium D processors feature a locked clock frequency multiplier. It means that these CPUs should be overclocked by raising the FSB bus frequency. In other words, the overclocker’s system should feature a very high-quality mainboard that will allow significant increase in the FSB frequency without threatening the system stability.

Another important thing that we revealed during our experiments, is the serious dependence of the Pentium D (Presler) overclocking potential on the Vcore. Higher Vcore could only slightly expand the processor’s supported frequency range in case of Intel processors with 90nm cores. However, now that we have moved to 65nm Presler, the situation has become totally different. This core appears very sensitive to Vcore increase. As a result, Pentium D overclocking with the help of specific cooling solutions such as phase cooling or water cooling could be very efficient, because it would allow increasing the processor Vcore quite significantly. For example, the results obtained by the best overclockers out there show that Presler can go as high as 5.5-6GHz on the core.

As for us, we are not going to deal with any high-tech cooling devices. We are just going to see, how far we could go with a mass air-cooler. Of course, the maximum working frequencies of the Presler based processors will be much lower in this case. For instance, when we overclocked a Pentium Extreme Edition on this core, we managed to reach 4.26GHz with the air cooling system installed. To be honest, we expected to see something similar today with our Pentium D 920 and Pentium D 930 processors.

The first one to go was Pentium D 920 CPU. The maximum GSB frequency when the CPU could work stably without raising the Vcore equaled 268MHz. In other words, at the nominal core voltage this processor could work at the frequency slightly higher than the nominal: 3.75GHz. However, as we have already mentioned above, the increase in Preselr’s Vcore pushes its overclocking potential up enormously. So, all our further experiments were conducted with the processor Vcore increased to 1.45V. We could actually raise the Vcore even more in order to obtain more impressive results, however, we couldn’t risk losing the CPU, so we didn’t go any further. Especially, since we did not have any statistics about the safe operation of Pentium D with the greatly increased Vcore.