X-bit labs

First Look at Presler: Intel Pentium Extreme Edition 955 CPU Review (page 8)

Category: CPU

by Ilya Gavrichenkov

[ 12/27/2005 | 08:01 AM ]

Power Consumption

Intel set the same typical heat dissipation level for the new Pentium Extreme Edition 955 as they did for the Pentium Extreme Edition 840: 130W. So, both these CPUs should have similar power consumption rate. In other words, all the recommendations we have previously given you regarding the powerful power supply units and cooling systems for the systems built with dual-core Intel processors, are also valid for the systems with Intel Pentium Extreme Edition 955. But this is just the theory.

In practice, it would be very interesting to measure the power consumption of this CPU. It is based on the core manufactured with new technological process, which should make it less power-hungry anyway. So, we had to run these tests.

The diagram below shows the power consumption rates of the Pentium Extreme Edition 955 side by side with the results taken for the two top-end AMD and Intel processors manufactured with the 90nm technology. As always, we used a special S&M utility to measure the maximum power consumption (you can download this utility here ). We measured the current that goes through the CPU power circuitry. So, the numbers given below do not take into account the efficiency of the CPU voltage regulator laid out on the mainboard.

Presler processors are really more economical than their predecessors. Of course, there was no significant improvement, but the new Presler processor working at a higher frequency than Smithfield and featuring larger L2 cache still demonstrated about 13% lower power consumption. From the thermal and electrical prospective, this puts the new Pentium Extreme Edition 955 processor on the same level with the top single-core Intel CPUs, which feature lower claimed typical heat dissipation of 115W. So, Intel has ensured that there is some extra reserve for maneuvers, namely that they do not have to be very strict about the dies selection for the top of the line dual-core CPUs.

On the other hand, all this enthusiasm about the lower power consumption of the 65nm processor cores vanishes when we try to compare it against the competitor from AMD. Well, this is the peculiarity of the NetBurst architecture: it is not economical and there is nothing we can do about it.

I would also like to say a few words about the power consumption of Presler processor in idle mode. The thing is that Intel guys specifically stress some innovations introduced in the 65nm manufacturing technology that allow reducing the power consumption in idle mode. Namely, there are special sleep transistors, which stop sending power to those parts of the die that are not working at the moment. However, our measurements show that the power consumption in idle mode is about the same by Presler and Smithfield and equals about 50W.