The new manufacturing technology will undoubtedly be of interest to overclockers. Especially, since it implies higher clock frequency potential of the new processor cores, as we have already mentioned above. So, even if Intel is not going to increase the clock rates of the CPUs with NetBurst architecture, we will do that for them.
I have to say that when I was preparing to start our overclocking experiments on Presler processors this time, we didn’t aim at reaching the maximum clock speed at any rate. it is evident that the new CPUs on 65nm cores will be able to reach the highest frequencies with appropriate cooling solution, of course. However, one of the major reasons why Intel decided to give up the NetBurst architecture is exactly the increasing heat dissipation of the CPUs as their frequency goes up. In other words, extreme overclocking fans should definitely go for Presler CPUs for their experiments. With highly efficient cooling solutions you can overclock Presler based CPUs to 5.5GHz, which we know from the first reports made by some lucky computer enthusiasts. We were trying to solve a slightly different task in our lab. Our main goal was to find that maximum frequency, which will be attainable for any Presler based CPU owner without superior cooling involved. So, all our overclocking attempts of the new Pentium Extreme Edition 955 were carried out with the regular default CPU cooler.
First of all, I would like to say that dual-core Pentium Extreme Edition CPUs are quite convenient for overclocking. Intel doesn’t lock their nominal clock frequency multiplier that is why you can overclock these processors not only by increasing the bus frequency, but also by raising the clock frequency multiplier. This justifies partially for the high price of these processors and makes overclocking much simpler.
We assembled a system on ASUS P5WD2 Premium mainboard for our tests. It was equipped with a pair of Corsair CM2X1024-6400PRO memory modules. Besides, there was an NVIDIA GeForce 6800 GT graphics card and a Western Digital WD740GD HDD installed.
First we tried to increase the clock the frequency multiplier. It turned out that even with the nominal cooler, which is not that dramatically efficient, our Pentium Extreme Edition 955 works just fine without increasing the Vcore at up to 15x multiplier setting. Note that the processor frequency grew up to 4GHz in this case, which is 15% above the nominal. I have to admit that dual-core processors on 90nm cores couldn’t boast the same success.
As for the further frequency increase, unfortunately the system would lose stability once the multiplier was set to 16x. However, we haven’t yet tried to adjust the Vcore. Once we increased the Vcore to 1.375V, the CPU easily went over 4.26GHz.
Further experiments showed that the CPU can work stably without throttling at up to 4.3GHz frequency. So, it looks like 4.26GHz appears a pretty nice variant for mainstream systems equipped with no special cooling solutions.
The important thing about overclocking the CPU by 25% is the fact that all other system knots continued working in the nominal mode, because the CPU clock frequency was reached by simply raising the frequency multiplier from 13x to 16x. And since we managed to achieve these results so easily, we decided it would make sense to include them into the performance analysis as well (Pentium Extreme Edition 955 working at 4.26GHz (16 x 266MHz).
As for the thermal mode, the maximum temperature of the Pentium Extreme Edition 955 processor overclocked to 4.26GHz (under full workload) reached 79o C. When we measured the CPU temperature in the nominal mode, that is at 3.46GHz, it never went over 65o C. So, this indicates clearly that further frequency increase will require more efficient cooling solution onboard.