When Intel launched the P7 family of microprocessors six years ago using the NetBurst microarchitecture, it gambled on a long pipeline (initially 20 stages and later 31 stages) architecture in exchange for high clock rates. While many today are declaring the NetBurst obsolete and a failure, they're only half right. The end of the NetBurst era has finally come. The NetBurst architecture may have hit a thermal brick wall at 3.8 GHz (maybe 4.26 GHz with really good air cooling) and is definitely obsolete, but it's hardly a failure by any means.
The NetBurst was used in the massively successful Pentium 4 line of Intel CPUs and used in many of the XEON server processors but time has simply passed it by. The NetBurst architecture reached its zenith in 2003 when it ran away with clock speeds surpassing the 3 GHz mark while AMD's top of the line Athlon XP fell behind in performance at 2.1 GHz. Things were looking bright for Intel and stories of 4+ GHz Pentium 4 processors running in the lab somewhere made it seem like the Pentium 4 would scale the GHz tower forever. The problem for NetBurst is that it's been stuck in the 3 GHz range for the last 3 years while AMD enhanced their architecture with an on-chip memory controller and bumped their more efficient instruction per cycle processor up to 2.8 GHz. Within the last two years, AMD has been able to consistently beat Intel's Desktop and Server CPU performance while consuming less energy while has allowed AMD to grow rapidly at the expense of Intel. This has predictably caused AMD's stock to soar while Intel's stock plummeted.
During this same period of time, Intel's saving grace has been its Pentium M mobile processor based on the Dothan microarchitecture. The Pentium M design was a radical departure from the NetBurst architecture and used a short 10-stage pipeline. Not only was it far more power efficient than NetBurst and even AMD's Athlon, the Pentium M is even faster per clock cycle than AMD's newest Athlon 64. Case in point, an overclocked 2.48 GHz Pentium M running at a cool 25 watt TPD with crippled memory performance and no SSE3 capability managed to destroy an "Extreme Edition" Pentium 4 3.44 GHz CPU and a 2.6 GHz Athlon 64 FX-55 processor in virtually every video game on the market! While this was great for Intel in the mobile market, it couldn't help Intel in the Desktop and Server market because Intel was still squeezing the last penny out of the NetBurst architecture and Intel never marketed the Pentium M CPU for the Desktop or Server market.
With the announcements of the new "Core" architecture dual-core CPUs for Servers, Desktops, and Mobile platform at the IDF (Intel Developer Forum) this week, the end of the NetBurst era has finally come. The first generation of dual-core Core processors have already been integrated in to the new Intel-based Macs and WinTel notebooks from all the PC manufacturers, but the next generation of Core processors due in the second half of this year will officially signal the beginning of a new era. The next generation Core processors will be broken down in to Merom for the Mobile market, Conroe for the Desktop market, and Woodcrest for the Server market. These new Core processors take an already efficient Pentium M design and enhances it further by doing more work per clock cycle, higher clock speeds, EM64T capability for 32/64 bit support, and hardware Virtualization support called "VT".
When I spoke to an Intel representative at the IDF, he showed me a small low-power low-noise BTX running a Conroe dual-core processor at 2.66 GHz. Given how well the old single-core Pentium M CPU did at 2.48 GHz, the prospect of a dual-core enhanced efficiency 64 bit version of the Dothan architecture running at 2.66 GHz is astounding! When I asked the Intel Representative what the top speed for Conroe was going to be, he would only tell me that it would be higher than 2.66 GHz. If 2.66+ GHz Intel Core processors actually materialize in Q3 of 2006, this could spell big trouble for AMD whose stock fell 10% this week. Intel's next generation Core architecture will mean the death of the Pentium 4 and XEON processors. The question is whether AMD can survive the onslaught.