Intel's Pentium 4 3.06GHz: Hyper-Threading on Desktops

HT Enabled

It isn't a surprise to many that Hyper-Threading (HT) has been present on all Intel Pentium 4 CPUs, even those before today's 3.06GHz part. Remember that Hyper-Threading only accounted for < 5% of the Pentium 4's overall die size, so it didn't kill Intel to have HT on die but not enabled. The benefit of integrated HT into the Pentium 4's design from the start is obvious; once the technology is deemed ready for the mass-market, enabling it is simple and doesn't require any redesign of the CPU. Had the technology been ready back in 2000 we would've seen it debut with the Pentium 4, but not everything works out perfectly and thus only owners of the 3.06GHz CPU and future Pentium 4s will get Hyper-Threading support.

The graphic above illustrates clearly the additions to the core that had to be made in order to support Hyper-Threading; as you can see, the technology imposes next to no hardware changes on the Pentium 4 but the potential for performance increase is tremendous.

From a hardware standpoint taking advantage of Hyper-Threading simply requires the following:

We've explained the benefits of Hyper-Threading in great detail in previous articles, but just to recap we'll briefly explain the theory and the implementation here. For more detail be sure to read our previous pieces:

• Intel's Hyper-Threading Technology: Free Performance?
• Intel Developer Forum Fall 2002 - Hyper-Threading & Memory Roadmap
• Intel Developer Forum Fall 2002 - Day 2: More on Hyper-Threading
• Database Server CPU Comparison: Athlon MP vs. Hyper-Threading Xeon