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The New Intel 'Prescott' Processors
By CPU-zilla
Category : CPU
Published by Jimmy Tang on Tuesday, 3rd February, 2004
Rating : 3.5 out of 5 stars  


The 90nm Processor

The much-awaited "Prescott" processor is the first 90nm product from Intel hitting the streets today. Built on Intel's latest 90nm process technology, the Prescott processor is nothing more than just the familiar Pentium 4 processor. Now that the transistor size has been shrunk from 130nm (in Northwood) to 90nm, there is now more real estate space on the silicon die to fit extra transistors to further enhance the performance of this desktop-bound processor.

Most processors coming out of Intel's manufacturing facilities are built with their state-of-the-art 300mm wafer process. The further shrinkage of the transistors only mean that it would be much simpler and faster for Intel to ramp up their production of these products. In fact, there are already three 300mm fabs (D1C, F11X and F24) involved in helping Intel to quickly ramp the production of these processors based on the 90nm technology.

With the introduction of the new Pentium 4 "Prescott" processor, Moore's Law looks set to continue on the desktop side of things. Of course, we must not forget that the Itanium 2 with over 0.5 billion transistors is still the largest and most advanced silicon behemoth to ever exist today, not to mention that it's this particular product that's helping to keep Moore's Law on track. However, much of Moore's Law today is satisfied by the increase of the processor's cache size rather than the main functional parts of the ALU (arithmetic logic unit) and FPU (floating point unit). And it's the size of the cache that's mainly responsible for much of what Prescott contains.

The new Intel Pentium 4 "Prescott" processors.

Packed in a tiny silicon die of no more than 112mm², the processor is made up of a total of 125 million transistors. Compared with the Northwood, the Prescott has slightly more than two times the amount of transistors found in Northwood. Much of these transistors make up the large 1MB Level 2 cache which should help boost the performance of certain applications. The doubling of the L2 cache has been proven effective in performance as seen during the transition from the Willamette (256KB) to Northwood (512KB). Besides that, the introduction of Prescott would also bring the Pentium 4 to a level that is now on-par with most of AMD's Athlon 64 processor (except for their 3000+ model).

The table below will basically tell you what are some of the differences between some of today's desktop processors :-

Processor Specifications Compared
Processor Model AMD Athlon XP AMD Athlon 64 AMD Athlon 64 FX-51 Intel Pentium 4 Intel Pentium 4 Extreme Edition Intel Pentium 4 "Prescott"
Codename Barton SledgeHammer ClawHammer Northwood Northwood Prescott
Manufacturing Technology 0.13µm 0.13µm SOI 0.13µm SOI 0.13µm 0.13µm 90nm (0.09µm)
No. of Transistors 54.3 million 105 million 105 million 55 million 178 million 125 million
Die Size 101 mm² 193 mm² 193 mm² 146 mm² 237 mm² 112 mm²
Front Side Bus 400MHz - - 800MHz 800MHz 800MHz
L1 Cache (data + instruction) 64KB + 64KB 64KB + 64KB 64KB + 64KB 8KB + 12KB 8KB + 12KB 16KB + 12KB
L2 Cache 512KB full-speed 512KB/1MB full-speed 1MB full-speed 512KB full-speed 512KB full-speed 1MB full-speed
L3 Cache - - - - 2MB full-speed -
Clock Multiplier 10.5 - 11x 10 - 11x 11x 12 - 16x 16x - 17x 14 - 17x
Clock Frequency 2.1GHz - 2.2GHz 2GHz - 2.2GHz 2.2GHz 2.4GHz - 3.2GHz 3.2GHz - 3.4GHz 2.8GHz - 3.2GHz
Core Voltage 1.65V 1.5V 1.5V 1.475V - 1.550V 1.475V - 1.525V 1.25V - 1.40V
Current (Icc) - Max 41.4A - 46.5A 57.8A 57.4A 52.4A - 67.4A 72.3A* 78A - 91A
Thermal Design Power (Max) 68.3W - 76.8W 89W 89W 66.2W - 82.0W 93.9W* 89W - 103W
Form Factor Socket-462 Socket-754 Socket-940 Socket-478 Socket-478 Socket-478
* Values stated for 3.2GHz part only. Information not disclosed for 3.4GHz part at time of publication.

As you can see in the table above, the Prescott is the mainstream processor with the second highest number of transistors (the highest is still the Pentium 4 Extreme Edition series). Following closely behind is the newly introduced Hammer series from AMD which contains up to 105 million transistors. However, if you look at the Prescott's die size, you'll find that the processor's transistor density is almost two times higher than all of the 0.13µm parts we have today.

Other notable differences with the Prescott includes a lower core operating voltage of between 1.25 - 1.40V, a larger Level 1 data cache of 16KB (twice the size of current Pentium 4 processors) and a very much increased requirement for power. The latter is what troubles us most as not all of today's Socket-478 motherboards has the ability to supply a maximum of 91A or 103W. Although certain motherboard manufacturers have prepared themselves for this (for example, Gigabyte confirmed with us that their Dual Power System feature could address that with ease), not every manufacturer has such a foresight. As a result, there is already a steady stream of boards coming out from Taiwan that comes with an improved power supply to address the power-hungry Prescott processor. However, note that the current crop of Prescott processors at 3.4E GHz and below could still be used in all Socket-478 motherboards since its requirements are just hitting the ceiling of current FMB 1.0 specifications. But with the power circuits all pumping at its maximum capacity, we're honestly not too comfortable with that thought.

In addition to higher cache sizes, Intel also added a new set of instructions known as PNI (Prescott New Instructions) or SSE3. This set of 13 new instructions further enhance the processor's floating point performance and is especially targeted at media and gaming. Besides that, Intel also added two instructions to further enhance the Hyper-Threading performance. We'll take a look and see if that helped at all.

Prescott's New SSE3 Instructions
Function Instruction(s)
FP to Integer Conversions FISTTP
Complex Arithmetic ADDSUBPD, ADDSUBPS, MOVDDUP, MOVSHDUP, MOVSLDUP
Video Encoding LDDQU
SIMD FP Using AOS Format HADDPD, HSUBPD, HADDPS, HSUBPS
Thread Synchronization MONITOR, MWAIT

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