Intel Core i7: Nehalem and the Return of Hyper-Threading

For the last couple of years, Intel’s "Core 2 Duo" has been the king of the hill. But today, they’ve released the Core i7 (based on the Nehalem architecture), and it makes everything else look like a toy. It’s not just a faster Core 2; it’s a fundamental redesign of the PC architecture.

Integrated Memory Controller (IMC)

The biggest bottleneck in PCs for decades has been the "Front Side Bus" (FSB). The CPU had to go through a separate Northbridge chip to talk to RAM. Nehalem finally moves the memory controller onto the CPU itself.

With three channels of DDR3 memory, the bandwidth is astronomical. The "Core i7 920" (the entry-level model) has more memory bandwidth than the most expensive server chips from six months ago.

The Return of Hyper-Threading

Intel has also brought back "Hyper-Threading," which we last saw on the Pentium 4. But unlike the P4, where it often hurt performance, on the i7 it’s incredibly effective. A quad-core i7 appears to the OS as 8 logical processors.

Cores: 4
Threads: 8
L3 Cache: 8MB (Shared)
Turbo Boost: Dynamic overclocking based on load

The new "Turbo Boost" feature is another stroke of genius. If you’re running an older app that only uses one core, the CPU will automatically overclock that one core while keeping the others idle. It’s the best of both worlds: high single-thread performance and massive multi-thread throughput.

Looking Ahead

The Core i7 is the start of a new era where we stop talking about "FSB speeds" and start talking about "QPI" (QuickPath Interconnect). For developers, it’s a mandate to write more parallel code. If your app isn't threaded, you’re leaving 7/8ths of the power of this chip on the table. Intel has just set the bar for the next five years of workstation computing.